Movable body drive system and movable body drive method, pattern formation apparatus and method, exposure apparatus and method, device manufacturing method, and decision-making method

ABSTRACT

An exposure apparatus exposes a substrate with illumination light via a projection optical system, and includes a stage disposed below the projection optical system and holds the substrate; an encoder system in which one of a grating section and a head is provided at the stage and the other of the grating section and the head is provided at a frame member disposed above the stage, on a lower end side of the projection optical system, and which irradiates the grating section with a measurement beam via the head and measures positional information of the stage with a plurality of the heads that face the grating section; and a controller coupled to the encoder system, that controls a drive system based on positional information measured with the encoder system while compensating for measurement error of the encoder system related to measurement direction of the positional information by the heads.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Division of U.S. patent application Ser. No. 15/382,825 filedDec. 19, 2016, which in turn is a Division of U.S. patent applicationSer. No. 14/168,299 filed Jan. 30, 2014 (now U.S. Pat. No. 9,568,844),which is a Division of U.S. patent application Ser. No. 11/896,411 filedAug. 31, 2007 (now U.S. Pat. No. 8,675,171), which claims the benefit ofProvisional Application No. 60/853,750 filed Oct. 24, 2006. Thedisclosure of each of the prior applications is hereby incorporatedherein by reference in their entireties.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to movable body drive systems and movablebody drive methods, pattern formation apparatuses and methods, exposureapparatuses and methods, device manufacturing methods, anddecision-making methods, and more particularly to a movable body drivesystem and a movable body drive method that drive a movable body along apredetermined plane, a pattern formation apparatus equipped with themovable body drive system and a pattern formation method using themovable body drive method, an exposure apparatus equipped with themovable body drive system and an exposure method using the movable bodydrive method, a device manufacturing method using the pattern formationmethod, and a decision-making method in which correction information ofmeasurement values of an encoder system that measures positioninformation of a movable body in a predetermined direction is decided.

Description of the Background Art

Conventionally, in a lithography process in the manufacturing ofmicrodevices (electron devices) such as semiconductor devices and liquidcrystal display devices, exposure apparatuses such as a reductionprojection exposure apparatus by a step-and-repeat method (a so-calledstepper) and a reduction projection exposure apparatus by astep-and-scan method (a so-called scanning stepper (which is also calleda scanner) are relatively frequently used.

In these types of exposure apparatuses, in order to transfer a patternof a reticle (or mask) to a plurality of shot areas on a wafer, a waferstage that holds the wafer is driven in XY two-dimensional directionsby, for example, a linear motor or the like. In particular, in the caseof the scanning stepper, not only the wafer stage but also a reticlestage is driven by a linear motor or the like in a scanning direction ina predetermined stroke. Generally, position measurement of the reticlestage or the wafer stage is performed using a laser interferometer whosemeasurement values have stability for a long period and which has a highresolution.

However, more accurate position control performance has been requireddue to finer patterns to cope with higher integration of semiconductors,and recently the short-term fluctuation of the measurement values causedby variation in the temperature of the atmosphere on the beam opticalpath of the laser interferometer has been accounting for a large shareof the overlay budget.

Meanwhile, as an apparatus other than the laser interferometer to beused for position measurement of a stage, an encoder can be cited, butbecause the encoder uses scales and the scales lack mechanical long-termstability (due to drift of scale pitch, fixed position drift, thermalexpansion, and the like), and therefore, the encoder suffers from thedisadvantages of lacking the linearity of the measurement values andbeing inferior in the long-term stability, compared with the laserinterferometer.

In view of the disadvantages of the laser interferometer and the encoderas described above, various types of apparatuses that measure theposition of a stage using both a laser interferometer and a positiondetection sensor (encoder) that uses a diffraction grating have beenproposed (refer to Kokai (Japanese Unexamined Patent ApplicationPublications) No. 2002-151405 and No. 2004-101362, and the like.)

Further, although a measurement resolution of a conventional encoder wasinferior to that of an interferometer, recently encoders having themeasurement resolution equal or superior to the laser interferometershave come out (e.g. refer to Kokai (Japanese Unexamined PatentApplication Publication) No. 2005-308592 and the like), and thetechnique of combining the laser interferometer and the encoder has beengathering attention.

However, for example, in the case the encoder is used for positionmeasurement of a wafer stage within a moving plane in an exposureapparatus, even when the position of a stage on which a scale (grating)is arranged is measured using one encoder head, if the relative motionbetween the head and the scale occurs in a direction other than adirection to be measured (measurement direction), the variation in themeasurement value (count) is detected and a measurement error occurs inmost cases. In addition, in the case the encoder is actually applied toa wafer stage of an exposure apparatus, because a plurality of encoderheads need to be used for one scale, there is also the inconveniencethat an error occurs in a count value of the encoder due to, forexample, the difference in gradient (tilt of the optical axis) betweenthe encoder heads, and the like.

SUMMARY OF THE INVENTION

The inventor and the like perform various simulations in order to knoweffects of the relative displacement of a head and a scale in anon-measurement direction on the encoder measurement values whenmeasuring the position of a stage of the exposure apparatus by areflective-type optical encoder. As the result of the simulations, ithas been discovered that the count values of the encoder havesensitivity to the attitude change of the stage in a pitching directionand a yawing direction, and in addition, the count values also depend onthe positional change in a direction orthogonal to a moving plane of thestage.

The present invention has been made based on the results of theabove-described simulations performed by the inventor and the like, andaccording to a first aspect of the present invention, there is provideda movable body drive system that drives a movable body substantiallyalong a predetermined plane, the system comprising: an encoder that hasa head that irradiates a detection light to a scale having a gratingwhose periodic direction is a predetermined direction parallel to thepredetermined plane and receives a reflected light from the scale, andmeasures position information of the movable body in the predetermineddirection; and a drive unit that drives the movable body in thepredetermined direction, based on a measurement value of the encoder,and correction information in accordance with position information ofthe movable body in a direction different from the predetermineddirection at the time of the measurement.

With this system, the drive unit drives the movable body in apredetermined direction (measurement direction), based on a measurementvalue of the encoder that measures position information of the movablebody in the predetermined direction and based on correction informationin accordance with position information of the movable body in adirection (non-measurement direction) different from the predetermineddirection at the time of the measurement. That is, the movable body isdriven in a predetermined direction based on the measurement value ofthe encoder whose measurement error caused by the relative displacementof the head and the scale in the non-measurement direction has beencorrected by the correction information. Accordingly, the movable bodycan be driven in a predetermined direction with high accuracy, withoutbeing affected by the relative motion between the head and the scale indirections other than a direction to be measured (measurementdirection).

According to a second aspect of the present invention, there is provideda pattern formation apparatus, comprising: a movable body on which anobject is mounted and which can move substantially along a moving plane,holding the object; a patterning unit that generates a pattern on theobject; and the movable body drive system of the present invention thatdrives the movable body for pattern formation on the object.

With this apparatus, the patterning unit generates a pattern on anobject on the movable body that is driven with high accuracy by themovable body drive system of the present invention, so that the patterncan be formed with high accuracy on the object.

According to a third aspect of the present invention, there is provideda first exposure apparatus that forms a pattern on an object byirradiation of an energy beam, the apparatus comprising: a patterningunit that irradiates the energy beam to the object; and the movable bodydrive system of the present invention, wherein driving of the movablebody on which the object is mounted by the movable body drive system isperformed for relative movement of the energy beam and the object.

With this apparatus, for the relative movement of an energy beamirradiated from the patterning unit to the object and the object, themovable body drive system of the present invention accurately drives themovable body on which the object is mounted. Accordingly, a pattern canbe formed on the object with high accuracy by scanning exposure.

According to a fourth aspect of the present invention, there is provideda second exposure apparatus that exposes an object with an energy beam,the apparatus comprising: a movable body that can move in at least firstand second directions that are orthogonal to each other within apredetermined plane, holding the object; an encoder system in which oneof a grating section and a head unit is arranged on a surface of themovable body on which the object is held and the other of the gratingsection and the head unit is arranged facing the surface of the movablebody, and which measures position information of the movable body in atleast one of the first and second directions; and a drive unit thatdrives the movable body within the predetermined plane based onmeasurement information of the encoder system and position informationof the movable body in a different direction from the first and thesecond directions.

With this apparatus, the movable body can be driven with high accuracyin a measurement direction of the encoder system, without being affectedby the displacement of the movable body in directions other than themeasurement direction of the encoder system, and therefore the objectheld on the movable body can be exposed with high accuracy.

According to a fifth aspect of the present invention, there is provideda third exposure apparatus that exposes an object with an energy beam,the apparatus comprising: a movable body that can move in at least firstand second directions that are orthogonal to each other within apredetermined plane and can incline with respect to the predeterminedplane, holding the object; an encoder system in which one of a gratingsection and a head unit is arranged on a surface of the movable body onwhich the object is held and the other of the grating section and thehead unit is arranged facing the surface of the movable body, and whichmeasures position information of the movable body in at least one of thefirst and second directions; and a drive unit that drives the movablebody within the predetermined plane based on measurement information ofthe encoder system and inclination information of the movable body.

With this apparatus, the movable body can accurately be driven in ameasurement direction of the encoder system without being affected bythe inclination (displacement in the inclination direction) of themovable body, and therefore the object held on the movable body can beexposed with high accuracy.

According to a sixth aspect of the present invention, there is provideda fourth exposure apparatus that exposes an object with an energy beam,the apparatus comprising: a movable body that can move in at least firstand second directions that are orthogonal to each other within apredetermined plane, holding the object; an encoder system in which oneof a grating section and a head unit is arranged on a surface of themovable body on which the object is held and the other of the gratingsection and the head unit is arranged facing the surface of the movablebody, and which measures position information of the movable body in atleast one of the first and second directions; and a drive unit thatdrives the movable body within the predetermined plane based onmeasurement information of the encoder system and characteristicinformation of the head unit that is a factor causing a measurementerror of the encoder system.

With this apparatus, the movable body can accurately be driven in ameasurement direction of the encoder system without being affected bythe measurement error of the encoder system caused by (characteristicsof) the head unit, and therefore the object held on the movable body canbe exposed with high accuracy.

According to a seventh aspect of the present invention, there isprovided a fifth exposure apparatus that exposes an object with anenergy beam, the apparatus comprising: a movable body that can move inat least first and second directions that are orthogonal to each otherwithin a predetermined plane, holding the object; an encoder system inwhich one of a grating section and a head unit is arranged on a surfaceof the movable body on which the object is held and the other of thegrating section and the head unit is arranged facing the surface of themovable body, and which measures position information of the movablebody in at least one of the first and second directions; and a driveunit that drives the movable body within the predetermined plane basedon measurement information of the encoder system so that a measurementerror of the encoder system that occurs due to the head unit iscompensated.

With this apparatus, the movable body can accurately be driven in ameasurement direction of the encoder system without being affected bythe measurement error of the encoder system that occurs due to the headunit, and therefore the object held on the movable body can be exposedwith high accuracy.

According to an eighth aspect of the present invention, there isprovided a movable body drive method in which a movable body is drivensubstantially along a predetermined plane, the method including: aprocess of measuring position information of the movable body in apredetermined direction parallel to the predetermined plane using anencoder that has a head that irradiates a detection light to a scalehaving a grating whose periodic direction is the predetermined directionand receives a reflected light from the scale, and of driving themovable body in the predetermined direction based on a measurement valueof the encoder and correction information in accordance with positioninformation of the movable body in a direction different from thepredetermined direction at the time of the measurement.

With this method, the movable body is driven in a predetermineddirection based on the measurement value of the encoder whosemeasurement error caused by the relative displacement of the head andthe scale in the non-measurement direction has been corrected by thecorrection information. Accordingly, the movable body can be driven in apredetermined direction with high accuracy, without being affected bythe relative motion between the head and the scale in directions otherthan a direction to be measured (measurement direction).

According to a ninth aspect of the present invention, there is provideda pattern formation method, including: a process of mounting an objecton a movable body that can move within a moving plane; and a process ofdriving the movable body in the movable body drive method of the presentinvention in order to form a pattern on the object.

With this method, a pattern is formed on the object mounted on themovable body that is driven with high accuracy using the movable bodydrive method of the present invention, and accordingly the pattern canbe formed on the object with high accuracy.

According to a tenth aspect of the present invention, there is provideda first device manufacturing method including a pattern formationprocess, wherein in the pattern formation process, a pattern is formedon a substrate using the pattern formation method of the presentinvention.

According to an eleventh aspect of the present invention, there isprovided a first exposure method in which a pattern is formed on anobject by irradiation of an energy beam, the method including: driving amovable body on which the object is mounted using the movable body drivemethod of the present invention, for relative movement of the energybeam and the object.

With this method, for the relative movement of the energy beamirradiated to the object and the object, the movable body on which theobject is mounted is driven with high accuracy using the movable bodydrive method of the present invention. Accordingly, a pattern can beformed on the object with high accuracy by scanning exposure.

According to a twelfth aspect of the present invention, there isprovided a second exposure method in which an object is exposed with anenergy beam, the method including: mounting the object on a movable bodythat can move in at least first and second directions that areorthogonal to each other within a predetermined plane; and driving themovable body within the predetermined plane, based on measurementinformation of an encoder system in which one of a grating section and ahead unit is arranged on a surface of the movable body on which theobject is mounted and the other of the grating section and the head unitis arranged facing the surface of the movable body, and which measuresposition information of the movable body in at least one of the firstand second directions, and based on position information of the movablebody in a different direction from the first and the second directions.

With this method, the movable body can accurately be driven in ameasurement direction of the encoder system without being affected bythe displacement of the movable body in directions other than themeasurement direction of the encoder system, and therefore the objectheld on the movable body can be exposed with high accuracy.

According to a thirteenth aspect of the present invention, there isprovided a third exposure method in which an object is exposed with anenergy beam, the method including: mounting the object on a movable bodythat can move in at least first and second directions that areorthogonal to each other within a predetermined plane and can inclinewith respect to the predetermined plane; and driving the movable bodywithin the predetermined plane, based on measurement information of anencoder system in which one of a grating section and a head unit isarranged on a surface of the movable body on which the object is mountedand the other of the grating section and the head unit is arrangedfacing the surface of the movable body, and which measures positioninformation of the movable body in at least one of the first and seconddirections, and based on inclination information of the movable body.

With this method, the movable body can accurately be driven in ameasurement direction of the encoder system without being affected bythe inclination (displacement in the inclination direction) of themovable body, and therefore the object held on the movable body can beexposed with high accuracy.

According to a fourteenth aspect of the present invention, there isprovided a fourth exposure method in which an object is exposed with anenergy beam, the method including: mounting the object on a movable bodythat can move in at least first and second directions that areorthogonal to each other within a predetermined plane; and driving themovable body within the predetermined plane, based on measurementinformation of an encoder system in which one of a grating section and ahead unit is arranged on a surface of the movable body on which theobject is mounted and the other of the grating section and the head unitis arranged facing the surface of the movable body, and which measuresposition information of the movable body in at least one of the firstand second directions, and based on characteristic information of thehead unit that is a factor causing a measurement error of the encodersystem.

With this method, the movable body can accurately be driven in ameasurement direction of the encoder system without being affected bythe measurement error of the encoder system caused by (characteristicsof) the head unit, and therefore the object held on the movable body canbe exposed with high accuracy.

According to a fifteenth aspect of the present invention, there isprovided a fifth exposure method in which an object is exposed with anenergy beam, the method including: mounting the object on a movable bodythat can move in at least first and second directions that areorthogonal to each other within a predetermined plane; and driving themovable body within the predetermined plane, based on measurementinformation of an encoder system in which one of a grating section and ahead unit is arranged on a surface of the movable body on which theobject is mounted and the other of the grating section and the head unitis arranged facing the surface of the movable body, and which measuresposition information of the movable body in at least one of the firstand second directions, so that a measurement error of the encoder systemthat occurs due to the head unit is compensated.

With this method, the movable body can accurately be driven in ameasurement direction of the encoder system without being affected bythe measurement error of the encoder system that occurs due to the headunit, and therefore the object held on the movable body can be exposedwith high accuracy.

According to a sixteenth aspect of the present invention, there isprovided a second device manufacturing method including a lithographyprocess, wherein in the lithography process, a sensitive object isexposed and a pattern is formed on the sensitive object using any one ofthe second to fifth exposure methods of the present invention.

According to a seventeenth aspect of the present invention, there isprovided a first decision-making method in which correction informationof a measurement value of an encoder system is decided, the encodersystem having a head, which irradiates a detection light to a scale thatis arranged on a movable body capable of moving substantially along apredetermined plane and that has a grating whose periodic direction is apredetermined direction within a plane parallel to the predeterminedplane and which receives a reflected light from the scale, and measuringposition information of the movable body in the predetermined direction,the method including: a process of performing sampling of measurementresults of the encoder system, in which an attitude of the movable bodyis changed to a plurality of different attitudes, the movable body ismoved in a predetermined stroke range in a direction orthogonal to thepredetermined plane while irradiating a detection light from the head toa specific area of the scale in a state where the attitude of themovable body is maintained, and the sampling of the measurement resultsis performed during the movement of the movable body with respect toeach of the attitudes; and a process of obtaining correction informationof a measurement value of the encoder system in accordance with positioninformation of the movable body in a direction different from thepredetermined direction by performing a predetermined computation basedon results of the sampling.

With this method, the attitude of the movable body is changed to aplurality of different attitudes, the movable body is moved in apredetermined stroke range in a direction orthogonal to thepredetermined plane while irradiating a detection light form the head toa specific area of the scale in a state of maintaining the attitude ofthe movable body, and the sampling of measurement results of the encodersystem is performed during the movement with respect to each of theattitudes. With this operation, variation information (e.g.characteristic curve) of measurement values of the encoder systemaccording to the position of the movable body in a direction orthogonalto the predetermined plane can be obtained for each attitude. Then, byperforming a predetermined computation based on the result of thesampling, that is, variation information of measurement values of theencoder system according to the position of the movable body in adirection orthogonal to the predetermined plane for each attitude,correction information of measurement values of the encoder systemaccording to the position information of the movable body in directions(non-measurement directions) different from a predetermined direction isobtained. Accordingly, correction information for correcting themeasurement error of the encoder system caused by the relative variationof the head and the scale in the non-measurement direction can bedecided in the simple method.

According to an eighteenth aspect of the present invention, there isprovided a second decision-making method in which correction informationof a measurement value of an encoder system equipped with a head unit isdecided, the head unit having a plurality of heads each of whichirradiates a detection light to a scale, which is arranged on a movablebody capable of moving substantially along a predetermined plane andwhose periodic direction is a predetermined direction within a planeparallel to the predetermined plane, and receives a reflected light fromthe scale, and constituting a plurality of encoders each of whichmeasures position information of the movable body in the predetermineddirection, the method including: a process of performing, to each of theplurality of heads, changing of an attitude of the movable body to aplurality of different attitudes, moving of the movable body in apredetermined stroke range in a direction orthogonal to thepredetermined plane while irradiating a detection light from a subjecthead to a specific area of the scale in a state where the attitude ofthe movable body is maintained, and sampling of measurement results ofthe encoder constituted by the subject head during the movement withrespect to each of the attitudes; and a process of obtaining correctioninformation of a measurement value of each of the plurality of encodersin accordance with position information of the movable body in adirection different from the predetermined direction by performing apredetermined computation based on results of the sampling.

Accordingly, in the simple method, correction information for correctingthe measurement error of the encoder system caused by the relativevariation of the head and the scale in the non-measurement direction canbe decided, and also correction information for also correcting ageometric measurement error (cosine error) caused by the gradient ofeach head can be decided.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings;

FIG. 1 is a view schematically showing the configuration of an exposureapparatus related to an embodiment;

FIG. 2 is a plan view showing a stage unit in FIG. 1;

FIG. 3 is a plan view showing the placement of various measurementapparatuses (such as encoders, alignment systems, a multipoint AFsystem, and Z sensors) that are equipped in the exposure apparatus inFIG. 1;

FIG. 4A is a plan view showing a wafer stage, and FIG. 4B is a schematicside view showing a partial cross section of wafer stage WST;

FIG. 5A is a plan view showing a measurement stage, and FIG. 5B is aschematic side view showing a partial cross section of the measurementstage;

FIG. 6 is a block diagram showing the main configuration of a controlsystem of the exposure apparatus related to an embodiment;

FIGS. 7A and 7B are views used to explain position measurement within anXY plane of a wafer table by a plurality of encoders each including aplurality of heads placed in the array arrangement, and the transfer ofmeasurement values between the heads;

FIG. 8A is a view showing an example of the configuration of theencoder, and FIG. 8B is a view used to explain the mechanism in whichmeasurement errors occur and to explain a relation between an incidentlight and a diffracted light of a beam with respect to a reflectivediffraction grating within an encoder head;

FIG. 9A is a view showing the case where a count value does not changeeven when the relative motion in a non-measurement direction occursbetween the head and the scale of the encoder, and FIG. 9B is a viewshowing an example of the case where a count value changes when therelative motion in a non-measurement direction occurs between the headand the scale of the encoder;

FIGS. 10A to 10D are views used to explain the case where a count valueof the encoder changes and the case where the count value does notchange, when the relative motion in a non-measurement direction occursbetween the head and the scale;

FIGS. 11A and 11B are views used to explain an operation for acquiringcorrection information used to correct a measurement error of an encoder(a first encoder) caused by the relative motion of the head and thescale in a non-measurement direction;

FIG. 12 is a graph showing measurement errors of the encoder withrespect to the change in the Z-position when a pitching amount θx equalsto α (θx=α);

FIG. 13 is a view used to explain an operation for acquiring correctioninformation used to correct a measurement error of another encoder (asecond encoder) caused by the relative motion of the head and the scalein a non-measurement direction;

FIG. 14 is a view showing a state of the wafer stage and the measurementstage when exposure by a step-and-scan method is being performed to awafer on the wafer stage;

FIG. 15 is a view showing a state of the wafer stage and the measurementstage immediately after a state of both stages shifts from the state inwhich both stages are separate from each other to a state in which bothstages come into contact with each other, after exposure is finished;

FIG. 16 is a view showing a state of the wafer stage and the measurementstage when the measurement stage is moving in the −Y direction and thewafer stage is moving toward an unloading position while keeping thepositional relation between both stages in the Y-axis direction;

FIG. 17 is a view showing a state of the wafer stage and the measurementstage when the measurement stage has reached a position where a Sec-BCHK(interval) is performed;

FIG. 18 is a view showing a state of the wafer stage and the measurementstage when the wafer stage has moved from the unloading position to aloading position in parallel with the Sec-BCHK (interval) beingperformed;

FIG. 19 is a view showing a state of the wafer stage and the measurementstage when the measurement stage has moved to an optimal scrum waitingposition and a wafer has been loaded on the wafer table;

FIG. 20 is a view showing a state of both stages when the wafer stagehas moved to a position where the Pri-BCHK former process is performedwhile the measurement stage is waiting at the optimal scrum waitingposition;

FIG. 21 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in three first alignment shot areasare being simultaneously detected using alignment systems AL1, AL2 ₂ andAL2 ₃;

FIG. 22 is a view showing a state of the wafer stage and the measurementstage when the focus calibration former process is being performed;

FIG. 23 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in five second alignment shot areasare being simultaneously detected using alignment systems AL1 and AL2 ₁to AL2 ₄;

FIG. 24 is a view showing a state of the wafer stage and the measurementstage when at least one of the Pri-BCHK latter process and the focuscalibration latter process is being performed;

FIG. 25 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in five third alignment shot areasare being simultaneously detected using alignment systems AL1 and AL2 ₁to AL2 ₄;

FIG. 26 is a view showing a state of the wafer stage and the measurementstage when alignment marks arranged in three fourth alignment shot areasare being simultaneously detected using alignment systems AL1, AL2 ₂ andAL2 ₃;

FIG. 27 is a view showing a state of the wafer stage and the measurementstage when the focus mapping has been finished;

FIG. 28 is a flowchart used to explain an embodiment of a devicemanufacturing method; and

FIG. 29 is a flowchart showing a specific example of step 204 in FIG.28.

DESCRIPTION OF THE EMBODIMENTS

An embodiment of the present invention will be described below, withreference to FIGS. 1 to 27.

FIG. 1 schematically shows the configuration of an exposure apparatus100 related to an embodiment. Exposure apparatus 100 is a scanningexposure apparatus by a step-and-scan method, that is, a so-calledscanner. As will be described later, in the embodiment, a projectionoptical system PL is arranged, and the following description will bemade assuming that a direction parallel to an optical axis AX ofprojection optical system PL is a Z-axis direction, a direction in whicha reticle and a wafer are relatively scanned within a plane orthogonalto the Z-axis direction is a Y-axis direction and a direction that isorthogonal to a Z-axis and a Y-axis is an X-axis direction, and rotation(tilt) directions around the X-axis, the Y-axis and the Z-axis are ex,θy and θz directions respectively.

Exposure apparatus 100 includes an illumination system 10, a reticlestage RST that holds a reticle R that is illuminated by an illuminationlight for exposure (hereinafter, referred to as “illumination light” or“exposure light”) IL from illumination system 10, a projection unit PUthat includes projection optical system PL that projects illuminationlight IL emitted from reticle R on a wafer W, a stage unit 50 that has awafer stage WST and a measurement stage MST, their control system, andthe like. On wafer stage WST, wafer W is mounted.

Illumination system 10 includes a light source and an illuminationoptical system that has an illuminance uniformity optical systemcontaining an optical integrator and the like, and a reticle blind andthe like (none of which is shown), as is disclosed in, for example,Kokai (Japanese Unexamined Patent Application Publication) No.2001-313250 (the corresponding U.S. Patent Application Publication No.2003/0025890) and the like. In illumination system 10, a slit-shapedillumination area IAR that is defined by the reticle blind (maskingsystem) and extends in the X-axis direction on reticle R is illuminatedby illumination light (exposure light) IL with substantially uniformilluminance. In this case, as illumination light IL, an ArF excimerlaser light (wavelength: 193 nm) is used as an example. Further, as theoptical integrator, for example, a fly-eye lens, a rod integrator(internal reflection type integrator), a diffraction optical element orthe like can be used.

On reticle stage RST, reticle R having a pattern surface (the lowersurface in FIG. 1) on which a circuit pattern and the like are formed isfixed by, for example, vacuum suction. Reticle stage RST is finelydrivable within an XY plane and also drivable at designated scanningvelocity in a predetermined scanning direction (which is the Y-axisdirection being a horizontal direction of the page surface of FIG. 1),by a reticle stage drive system 11 (not shown in FIG. 1, refer to FIG.6) including, for example, a linear motor or the like.

Position information of reticle stage RST within the moving plane(including rotation information in the θz direction) is constantlydetected at a resolution of, for example, around 0.5 to 1 nm with areticle laser interferometer (hereinafter, referred to as a “reticleinterferometer”) 116 via a movable mirror 15 (in actual, a Y movablemirror having a reflection surface orthogonal to the Y-axis directionand an X movable mirror having a reflection surface orthogonal to theX-axis direction are arranged). The measurement values of reticleinterferometer 116 are sent to a main controller 20 (not shown in FIG.1, refer to FIG. 6). Main controller 20 controls the position (and thevelocity) of reticle stage RST by computing the position of reticlestage RST in the X-axis direction, the Y-axis direction and the θzdirection based on the measurement values of reticle interferometer 116,and controlling reticle stage drive system 11 based on the computationresults. Incidentally, instead of movable mirror 15, the end surface ofreticle stage RST may be polished in order to form a reflection surface(corresponding to the reflection surface of movable mirror 15). Further,reticle interferometer 116 may be capable of also measuring positioninformation of reticle stage RST in at least one of the Z-axis, θx andθy directions.

Projection unit PU is placed below reticle stage RST in FIG. 1.Projection unit PU includes a barrel 40 and projection optical system PLhaving a plurality of optical elements that are held in a predeterminedpositional relation within barrel 40. As projection optical system PL,for example, a dioptric system that is composed of a plurality of lenses(lens elements) that are arrayed along an optical axis AX directionparallel to the Z-axis direction is used. Projection optical system PLis, for example, both-side telecentric and has a predeterminedprojection magnification (such as one-quarter, one-fifth or one-eighthtimes). Therefore, when illumination area IAR is illuminated byillumination light IL from illumination system 10, illumination light ILhaving passed through reticle R whose pattern surface is placedsubstantially coincidently with a first surface (object surface) ofprojection optical system PL forms a reduced image of a circuit pattern(a reduced image of part of a circuit pattern) of reticle R withinillumination area IAR on an area (exposure area) IA that is conjugatewith illumination area IAR on wafer W, which is placed on a secondsurface (image plane) side of projection optical system PL and whosesurface is coated with resist (photosensitive agent), via projectionoptical system PL (projection unit PU) and liquid Lq (refer to FIG. 1).Then, by synchronous driving reticle stage RST and wafer stage WST, thereticle is moved in the scanning direction (Y-axis direction) relativelyto illumination area IAR (illumination light IL) and also wafer W ismoved in the scanning direction (Y-axis direction) relatively to theexposure area (illumination light IL), and thus scanning exposure isperformed to one shot area (divided area) on wafer W and a pattern ofthe reticle is transferred to the shot area. That is, in the embodiment,a pattern is generated on wafer W by illumination system 10, the reticleand projection optical system PL, and the pattern is formed on the waferby exposure of a sensitive layer (resist layer) on wafer W byillumination light IL. Although not shown in the drawing, projectionunit PU is mounted on a barrel platform that is supported by threesupport columns via a vibration isolation mechanism. As is disclosed in,for example, the pamphlet of International Publication No. WO2006/038952, however, projection unit PU may also be supported in asuspended state with respect to a main frame member (not shown) that isplaced above projection unit PU, or a base member on which reticle stageRST is placed.

Further, in exposure apparatus 100 of the embodiment, in order toperform exposure applying the liquid immersion method, a nozzle unit 32that constitutes part of a local liquid immersion unit 8 is arranged soas to enclose the periphery of the lower end portion of barrel 40 thatholds an optical element that is closest to an image plane side (wafer Wside) that constitutes projection optical system PL, which is a lens(hereinafter, also referred to a “tip lens”) 191 in this case. In theembodiment, as is shown in FIG. 1, the lower end surface of nozzle unit32 is set to be substantially flush with the lower end surface of tiplens 191. Further, nozzle unit 32 is equipped with a supply opening anda recovery opening of liquid Lq, a lower surface to which wafer W isplaced facing and at which the recovery opening is arranged, and asupply flow channel and a recovery flow channel that are connected to aliquid supply pipe 31A and a liquid recovery pipe 31B respectively. Asis shown in FIG. 3, liquid supply pipe 31A and liquid recovery pipe 31Bare inclined at an angle of 45 degrees with respect to the X-axisdirection and the Y-axis direction in a planar view (when viewed fromabove) and are symmetrically placed with respect to a straight line LVin the Y-axis direction that passes through optical axis AX ofprojection optical system PL.

One end of a supply pipe (not shown) is connected to liquid supply pipe31A while the other end of the supply pipe is connected to a liquidsupply unit 5 (not shown in FIG. 1, refer to FIG. 6), and one end of arecovery pipe (not shown) is connected to liquid recovery pipe 31B whilethe other end of the recovery pipe is connected to a liquid recoveryunit 6 (not shown in FIG. 1, refer to FIG. 6).

Liquid supply unit 5 includes a liquid tank, a compression pump, atemperature controller, a valve for controlling supply/stop of theliquid to liquid supply pipe 31A, and the like. As the valve, forexample, a flow rate control valve is preferably used so that not onlythe supply/stop of the liquid but also the adjustment of flow rate canbe performed. The temperature controller adjusts the temperature of theliquid within the liquid tank to nearly the same temperature as thetemperature within the chamber (not shown) where the exposure apparatusis housed. Incidentally, the tank for supplying the liquid, thecompression pump, the temperature controller, the valve, and the like donot all have to be equipped in exposure apparatus 100, and at least partof them can also be substituted by the equipment or the like availablein the plant where exposure apparatus 100 is installed.

Liquid recovery unit 6 includes a liquid tank, a suction pump, a valvefor controlling recovery/stop of the liquid via liquid recovery pipe31B, and the like. As the valve, a flow rate control valve is preferablyused to correspond to the valve of liquid supply unit 5. Incidentally,the tank for recovering the liquid, the suction pump, the valve, and thelike do not all have to be equipped in exposure apparatus 100, and atleast part of them can also be substituted by the equipment available inthe plant where exposure apparatus 100 is installed.

In the embodiment, as the liquid described above, pure water(hereinafter, it will simply be referred to as “water” besides the casewhen specifying is necessary) that transmits the ArF excimer laser light(light with a wavelength of 193 nm) is to be used. Pure water can beobtained in large quantities at a semiconductor manufacturing plant orthe like without difficulty, and it also has an advantage of having noadverse effect on the photoresist on the wafer, to the optical lenses orthe like.

Refractive index n of the water with respect to the ArF excimer laserlight is around 1.44. In the water the wavelength of illumination lightIL is 193 nm×1/n, shorted to around 134 nm.

Liquid supply unit 5 and liquid recovery unit 6 each have a controller,and the respective controllers are controlled by main controller 20(refer to FIG. 6). According to instructions from main controller 20,the controller of liquid supply unit 5 opens the valve connected toliquid supply pipe 31A to a predetermined degree to supply water Lq tothe space between tip lens 191 and wafer W via liquid supply pipe 31A,the supply flow channel and the supply opening (refer to FIG. 1).Further, when the water is supplied, according to instructions from maincontroller 20, the controller of liquid recovery unit 6 opens the valveconnected to liquid recovery pipe 31B to a predetermined degree torecover water Lq from the space between tip lens 191 and wafer W intoliquid recovery unit 6 (the liquid tank) via the recovery opening, therecovery flow channel and liquid recovery pipe 31B. During the supplyand recovery operations, main controller 20 gives commands to thecontrollers of liquid supply unit 5 and liquid recovery unit 6 so thatthe quantity of water Lq supplied to the space between tip lens 191 andwafer W constantly equals the quantity of water Lq recovered from thespace. Accordingly, a constant quantity of water Lq is held in the spacebetween tip lens 191 and wafer W (refer to FIG. 1). In this case, waterLq held in the space between tip lens 191 and wafer W is constantlyreplaced.

As is obvious from the above description, in the embodiment, localliquid immersion unit 8 is configured including nozzle unit 32, liquidsupply unit 5, liquid recovery unit 6, liquid supply pipe 31A and liquidrecovery pipe 31B, and the like. Local liquid immersion unit 8 fills thespace between tip lens 191 and wafer W with water Lq using nozzle unit32 and forms a local liquid immersion space (corresponding to a liquidimmersion area 14) including an optical path space of illumination lightIL. Accordingly, nozzle unit 32 is also called a liquid immersion spaceforming member, a containment member (or confinement member) or thelike. Incidentally, part of local liquid immersion unit 8, for example,at least nozzle unit 32 may also be supported in a suspended state by amain frame (including the barrel platform described above) that holdsprojection unit PU, or may also be arranged at another frame member thatis separate from the main frame. Or, in the case projection unit PU issupported in a suspended state as is described earlier, nozzle unit 32may also be supported in a suspended state integrally with projectionunit PU, but in the embodiment, nozzle unit 32 is arranged on ameasurement frame that is supported in a suspended state independentlyfrom projection unit PU. In this case, projection unit PU does not haveto be supported in a suspended state.

Incidentally, also in the case measurement stage MST is located belowprojection unit PU, the space between a measurement table (to bedescribed later) and tip lens 191 can be filled with water in thesimilar manner to the above-described manner.

Incidentally, in the above description, one liquid supply pipe (nozzle)and one liquid recovery pipe (nozzle) are to be arranged as an example.However, the present invention is not limited to this, and aconfiguration having multiple nozzles as disclosed in, for example, thepamphlet of International Publication No. WO 99/49504, may also beemployed, in the case such arrangement is possible taking intoconsideration a relation with adjacent members. Further, a configurationmay also be employed in which the lower surface of nozzle unit 32 isplaced closer to the image plane of projection optical system PL (i.e.closer to the wafer) than the outgoing surface of tip lens 191, or anoptical path on the object plane side of tip lens 191 is also filledwith water in addition to an optical path on the image plane side of tiplens 191. The point is that any configuration may be employed as far asthe liquid can be supplied at least in the space between an opticalmember in the lowest end (tip lens) 191 constituting projection opticalsystem PL and wafer W. For example, the liquid immersion mechanismdisclosed in the pamphlet of International Publication No. WO2004/053955, or the liquid immersion mechanism disclosed in the EPPatent Application Publication No. 1 420 298 can also be applied to theexposure apparatus of the embodiment.

Referring back to FIG. 1, stage unit 50 is equipped with wafer stage WSTand measurement stage MST that are placed above a base board 12, aninterferometer system 118 (refer to FIG. 6) including Y interferometers16 and 18 and the like that measure position information of stages WSTand MST, an encoder system (to be described later) that is used formeasuring position information of wafer stage WST on exposure or thelike, a stage drive system 124 (refer to FIG. 6) that drives stages WSTand MST, and the like.

On the bottom surface of each of wafer stage WST and measurement stageMST, a noncontact bearing (not shown), for example, a vacuum preloadtype hydrostatic air bearing (hereinafter, referred to as an “air pad”)is arranged at a plurality of points. Wafer stage WST and measurementstage MST are supported in a noncontact manner via a clearance of aroundseveral μm above base board 12, by static pressure of pressurized airthat is blown out from the air pad toward the upper surface of baseboard 12. Further, stages WST and MST are independently drivabletwo-dimensionally in the Y-axis direction (a horizontal direction of thepage surface of FIG. 1) and the X-axis direction (an orthogonaldirection to the page surface of FIG. 1) within a predetermined plane(XY plane), by stage drive system 124.

To be more specific, as is shown in the plan view in FIG. 2, on a floorsurface, a pair of Y-axis stators 86 and 87 extending in the Y-axisdirection are respectively placed on one side and the other side in theX-axis direction having base board 12 in between. Y-axis stators 86 and87 are each composed of, for example, a magnetic pole unit thatincorporates a permanent magnet group that is made up of plural pairs ofa north pole magnet and a south pole magnet that are placed at apredetermined distance and alternately along the Y-axis direction. AtY-axis stators 86 and 87, two Y-axis movers 82 and 84, and two Y-axismovers 83 and 85 are respectively arranged in a noncontact engagedstate. In other words, four Y-axis movers 82, 84, 83 and 85 in total arein a state of being inserted in the inner space of Y-axis stator 86 or87 whose XZ sectional surface has a U-like shape, and are severallysupported in a noncontact manner via a clearance of, for example, aroundseveral μm via the air pad (not shown) with respect to correspondingY-axis stator 86 or 87. Each of Y-axis movers 82, 84, 83 and 85 iscomposed of, for example, an armature unit that incorporates armaturecoils placed at a predetermined distance along the Y-axis direction.That is, in the embodiment, Y-axis movers 82 and 84 made up of thearmature units and Y-axis stator 86 made up of the magnetic pole unitconstitute moving coil type Y-axis linear motors respectively.Similarly, Y-axis movers 83 and 85 and Y-axis stator 87 constitutemoving coil type Y-axis linear motors respectively. In the followingdescription, each of the four Y-axis linear motors described above willbe referred to as a Y-axis linear motor 82, a Y-axis linear motor 84, aY-axis linear motor 83 and a Y-axis linear motor 85 as needed, using thesame reference codes as their movers 82, 84, 83 and 85.

Movers 82 and 83 of two Y-axis linear motors 82 and 83 out of the fourY-axis linear motors are respectively fixed to one end and the other endin a longitudinal direction of an X-axis stator 80 that extends in theX-axis direction. Further, movers 84 and 85 of the remaining two Y-axislinear motors 84 and 85 are fixed to one end and the other end of anX-axis stator 81 that extends in the X-axis direction. Accordingly,X-axis stators 80 and 81 are driven along the Y-axis by a pair of Y-axislinear motors 82 and 83 and a pair of Y-axis linear motors 84 and 85respectively.

Each of X-axis stators 80 and 81 is composed of, for example, anarmature unit that incorporates armature coils placed at a predetermineddistance along the X-axis direction.

One X-axis stator, X-axis stator 81 is arranged in a state of beinginserted in an opening (not shown) formed at a stage main section 91(not shown in FIG. 2, refer to FIG. 1) that constitutes part of waferstage WST. Inside the opening of stage main section 91, for example, amagnetic pole unit, which has a permanent magnet group that is made upof plural pairs of a north pole magnet and a south pole magnet placed ata predetermined distance and alternately along the X-axis direction, isarranged. This magnetic pole unit and X-axis stator 81 constitute amoving magnet type X-axis linear motor that drives stage main section 91in the X-axis direction. Similarly, the other X-axis stator, X-axisstator 80 is arranged in a state of being inserted in an opening formedat a stage main section 92 that constitutes part of measurement stageMST. Inside the opening of stage main section 92, a magnetic pole unit,which is similar to the magnetic pole unit on the wafer stage WST side(stage main section 91 side), is arranged. This magnetic pole unit andX-axis stator 80 constitute a moving magnet type X-axis linear motorthat drives measurement stage MST in the X-axis direction.

In the embodiment, each of the linear motors described above thatconstitute stage drive system 124 is controlled by main controller 20shown in FIG. 6. Incidentally, each linear motor is not limited toeither one of the moving magnet type or the moving coil type, and thetypes can appropriately be selected as needed.

Incidentally, by making thrust forces severally generated by a pair ofY-axis linear motors 84 and 85 be slightly different, a yawing amount (arotation amount in the θz direction) of wafer stage WST can becontrolled. Further, by making thrust forces severally generated by apair of Y-axis linear motors 82 and 83 be slightly different, a yawingamount of measurement stage MST can be controlled.

Wafer stage WST includes stage main section 91 described above and awafer table WTB that is mounted on stage main section 91. Wafer tableWTB and stage main section 91 are finely driven in the Z-axis direction,the θx direction and the θy direction via a Z-leveling mechanism (notshown) (e.g. including a voice coil motor or the like) relatively tobase board 12 and X-axis stator 81. That is, wafer table WTB can moveminutely and can be inclined (tilted) in the Z-axis direction withrespect to the XY plane (or the image plane of projection opticalsystem). Incidentally, in FIG. 6, stage drive system 124 is shownincluding each of the linear motors and the Z-leveling mechanismdescribed above and a drive system of measurement stage MST. Further,wafer table WTB may be configured capable of minutely moving also in atleast one of the X-axis, Y-axis and ez directions.

On wafer table WTB, a wafer holder (not shown) that holds wafer W byvacuum suction or the like is arranged. The wafer holder may also beformed integrally with wafer table WTB, but in the embodiment, the waferholder and wafer table WTB are separately configured, and the waferholder is fixed inside a recessed portion of wafer table WTB, forexample, by vacuum suction or the like. Further, on the upper surface ofwafer table WTB, a plate (liquid repellent plate) 28 is arranged, whichhas the surface (liquid repellent surface) substantially flush with thesurface of a wafer mounted on the wafer holder to which liquid repellentprocessing with respect to liquid Lq is performed, has a rectangularouter shape (contour), and has a circular opening that is formed in thecenter portion and is slightly larger than the wafer holder (a mountingarea of the wafer). Plate 28 is made of materials with a low coefficientof thermal expansion, such as glasses or ceramics (such as Zerodur (thebrand name) of Schott AG, Al₂O₃, or TiC), and on the surface of plate28, a liquid repellent film is formed by, for example, fluorine resinmaterials, fluorine series resin materials such aspolytetrafluoroethylene (Teflon (registered trademark)), acrylic resinmaterials, or silicon series resin materials. Further, as is shown in aplan view of wafer table WTB (wafer stage WST) in FIG. 4A, plate 28 hasa first liquid repellent area 28 a whose outer shape (contour) isrectangular enclosing the circular opening, and a second liquidrepellent area 28 b that has a rectangular frame (annular) shape placedaround first liquid repellent area 28 a. On first liquid repellent area28 a, for example, when an exposure operation is performed, at leastpart of a liquid immersion area 14 protruding from the surface of thewafer is formed, and on second liquid repellent area 28 b, scales(grating sections) for an encoder system (to be described later) areformed. Incidentally, at least part of the surface of plate 28 does nothave to be flush with the surface of the wafer, that is, may have adifferent height from that of the surface of the wafer. Further, plate28 may be a single plate, but in the embodiment, plate 28 is configuredby combining a plurality of plates, for example, first and second liquidrepellent plates that correspond to first liquid repellent area 28 a andsecond liquid repellent area 28 b respectively. In the embodiment, purewater is used as liquid Lq as is described above, and therefore,hereinafter first liquid repellent area 28 a and second liquid repellentarea 28 b are also referred to as first water repellent plate 28 a andsecond water repellent plate 28 b.

In this case, exposure light IL is irradiated to first water repellentplate 28 a on the inner side, while exposure light IL is hardlyirradiated to second water repellent plate 28 b on the outer side.Taking this fact into consideration, in the embodiment, a first waterrepellent area to which water repellent coat having sufficientresistance to exposure light IL (light in a vacuum ultraviolet region,in this case) is applied is formed on the surface of first waterrepellent plate 28 a, and a second water repellent area to which waterrepellent coat having resistance to exposure light IL inferior to thefirst water repellent area is applied is formed on the surface of secondwater repellent plate 28 b. In general, since it is difficult to applywater repellent coat having sufficient resistance to exposure light IL(light in a vacuum ultraviolet region, in this case) to a glass plate,it is effective to separate the water repellent plate into two sectionsin this manner, i.e. first water repellent plate 28 a and second waterrepellent plate 28 b around it. Incidentally, the present invention isnot limited to this, and two types of water repellent coat that havedifferent resistance to exposure light IL may also be applied on theupper surface of the same plate in order to form the first waterrepellent area and the second water repellent area. Further, the samekind of water repellent coat may be applied to the first and secondwater repellent areas. For example, only one water repellent area mayalso be formed on the same plate.

Further, as is obvious from FIG. 4A, at the end portion on the +Y sideof first water repellent plate 28 a, a rectangular cutout is formed inthe center portion in the X-axis direction, and a measurement plate 30is embedded inside the rectangular space (inside the cutout) that isenclosed by the cutout and second water repellent plate 28 b. A fiducialmark FM is formed in the center in the longitudinal direction ofmeasurement plate 30 (on a centerline LL of wafer table WTB), and a pairof aerial image measurement slit patterns SL are formed in thesymmetrical placement with respect to the center of fiducial mark FM onone side and the other side in the X-axis direction of fiducial mark FM.As each of aerial image measurement slit patterns SL, an L-shaped slitpattern having sides along the Y-axis direction and X-axis direction canbe used, as an example.

Further, as is shown in FIG. 4B, at a portion of wafer stage WST beloweach of aerial image measurement slit patterns SL, an L-shaped housing36 inside which an optical system containing an objective lens, amirror, a relay lens and the like is housed is attached in a partiallyembedded state penetrating through part of the inside of wafer table WTBand stage main section 91. Housing 36 is arranged in pairs correspondingto the pair of aerial image measurement slit patterns SL, althoughomitted in the drawing.

The optical system inside housing 36 guides illumination light IL thathas been transmitted from above to below through aerial imagemeasurement slit pattern SL along an L-shaped route and emits the lighttoward a −Y direction. Incidentally, in the following description, theoptical system inside housing 36 is described as a light-transmittingsystem 36 by using the same reference code as housing 36 for the sake ofconvenience.

Moreover, on the upper surface of second water repellent plate 28 b,multiple grating lines are directly formed in a predetermine pitch alongeach of four sides. More specifically, in areas on one side and theother side in the X-axis direction of second water repellent plate 28 b(both sides in the horizontal direction in FIG. 4A), Y scales 39Y₁ and39Y₂ are formed respectively. Y scales 39Y₁ and 39Y₂ are each composedof a reflective grating (e.g. diffraction grating) having a periodicdirection in the Y-axis direction in which grating lines 38 having thelongitudinal direction in the X-axis direction are formed in apredetermined pitch along a direction parallel to the Y-axis (Y-axisdirection).

Similarly, in areas on one side and the other side in the Y-axisdirection of second water repellent plate 28 b (both sides in thevertical direction in FIG. 4A), X scales 39X₁ and 39X₂ are formedrespectively. X scales 39X₁ and 39X₂ are each composed of a reflectivegrating (e.g. diffraction grating) having a periodic direction in theX-axis direction in which grating lines 37 having the longitudinaldirection in the Y-axis direction are formed in a predetermined pitchalong a direction parallel to the X-axis (X-axis direction). As each ofthe scales, the scale made up of a reflective diffraction grating RG(FIG. 8A) that is created by, for example, hologram or the like on thesurface of second water repellent plate 28 b is used. In this case, eachscale has gratings made up of narrow slits, grooves or the like that aremarked at a predetermined distance (pitch) as graduations. The type ofdiffraction grating used for each scale is not limited, and not only thediffraction grating made up of grooves or the like that are mechanicallyformed, but also, for example, the diffraction grating that is createdby exposing interference fringe on a photosensitive resin may be used.However, each scale is created by marking the graduations of thediffraction grating, for example, in a pitch between 138 nm to 4 μm, forexample, a pitch of 1 μm on a thin plate shaped glass. These scales arecovered with the liquid repellent film (water repellent film) describedabove. Incidentally, the pitch of the grating is shown much wider inFIG. 4A than the actual pitch, for the sake of convenience. The same istrue also in other drawings.

In this manner, in the embodiment, since second water repellent plate 28b itself constitutes the scales, a glass plate with a low coefficient ofthermal expansion is to be used as second water repellent plate 28 b.However, the present invention is not limited to this, and a scalemember made up of a glass plate or the like with a low coefficient ofthermal expansion on which a grating is formed may also be fixed on theupper surface of wafer table WTB, for example, by a plate spring (orvacuum suction) or the like so as to prevent local shrinkage/expansion.In this case, a water repellent plate to which the same water repellentcoat is applied on the entire surface may be used instead of plate 28.Or, wafer table WTB may also be formed by materials with a lowcoefficient of thermal expansion, and in such a case, a pair of Y scalesand a pair of X scales may be directly formed on the upper surface ofwafer table WTB.

Mirror finish is severally applied to the −Y end surface and the −X endsurface of wafer table WTB, and a reflection surface 17 a and areflection surface 17 b shown in FIG. 2 are formed. By severallyprojecting an interferometer beam (measurement beam) to reflectionsurface 17 a and reflection surface 17 b and receiving a reflected lightof each beam, Y interferometer 16 and X interferometers 126, 127 and 128(X interferometers 126 to 128 are not shown in FIG. 1, refer to FIG. 2)that constitute part of interferometer system 118 (refer to FIG. 6)measure a displacement of each reflection surface from a datum position(generally, a fixed mirror is placed on the side surface of projectionunit PU, and the surface is used as a datum surface), that is, positioninformation of wafer stage WST within the XY plane, and supply themeasured position information to main controller 20. In the embodiment,as each of the interferometers, a multiaxial interferometer having aplurality of measurement axes is used as will be described later, exceptfor some of the interferometers.

Meanwhile, as is shown in FIGS. 1 and 4B, a movable mirror 41 having alongitudinal direction in the X-axis direction is attached to the −Yside surface of stage main section 91 via a kinematic support mechanism(not shown).

A pair of Z interferometers 43A and 43B constituting part ofinterferometer system 118 (refer to FIG. 6) that irradiate measurementbeams to movable mirror 41 are arranged opposing movable mirror 41(refer to FIGS. 1 and 2). To be more specific, as is obvious whenviewing FIGS. 2 and 4B together, movable mirror 41 is designed so that alength in the X-axis direction is longer than reflection surface 17 a ofwafer table WTB, by at least a distance between Z interferometers 43Aand 43B. Further, movable mirror 41 is made up of a member having ahexagon sectional shape, which seems to be formed by uniting arectangular and an isosceles trapezoid. Mirror finish is applied to the−Y side surface of movable mirror 41, and three reflection surfaces 41b, 41 a and 41 c are formed.

Reflection surface 41 a constitutes an end surface on the −Y side ofmovable mirror 41 and extends parallel to the XZ plane and in the X-axisdirection. Reflection surface 41 b constitutes an adjacent surface onthe +Z side of reflection surface 41 a and extends parallel to a planethat is inclined at an angle of predetermined degrees in a clockwisedirection in FIG. 4B with respect to XZ plane and in the X-axisdirection. Reflection surface 41 c constitutes an adjacent surface onthe −Z side of reflection surface 41 a and is arranged symmetricallywith reflection surface 41 b, with reflection surface 41 a in between.

As is obvious when viewing FIGS. 1 and 2 together, Z interferometers 43Aand 43B are respectively placed on one side and the other side of theX-axis direction of Y interferometer 16 at the substantially samedistance from Y interferometer 16, and at positions that are slightlylower than Y interferometer 16.

As is shown in FIG. 1, from each of Z interferometers 43A and 43B, ameasurement beam B1 along the Y-axis direction is projected towardreflection surface 41 b, and also a measurement beam B2 along the Y-axisdirection is projected toward reflection surface 41 c (refer to FIG.4B). In the embodiment, a fixed mirror 47A having a reflection surfaceorthogonal to measurement beam B1 that is reflected off reflectionsurface 41 b and fixed mirror 47B having a reflection surface orthogonalto measurement beam B2 that is reflected off reflection surface 41 c arearranged extending in the X-axis direction respectively, at positionsthat are spaced a predetermined distance apart from movable mirror 41 inthe −Y direction, in a state of not interfering with measurement beamsB1 and B2.

Fixed mirrors 47A and 47B are supported, for example, by the samesupport body (not shown) arranged on a frame (not shown) that supportsprojection unit PU. Incidentally, fixed mirrors 47A and 47B may also bearranged on the measurement frame described previously. Further, in theembodiment, movable mirror 41 having three reflection surfaces 41 b, 41a and 41 c, and fixed mirrors 47A and 47B are to be arranged, but thepresent invention is not limited to this. For example, a configurationmay also be employed in which a movable mirror having an inclinedsurface at an angle of 45 degrees is arranged on the side surface ofstage main section 91 and a fixed mirror is placed above wafer stageWST. In this case, the fixed mirror may be arranged on the support bodyor the measurement frame described above.

As is shown in FIG. 2, Y interferometer 16 projects measurement beams B4₁ and B4 ₂ to a reflection surface 17 a of wafer table WTB along themeasurement axes in the Y-axis direction that are spaced the samedistance apart on the −X side and the +X side from a straight lineparallel to the Y-axis passing through the projection center ofprojection optical system PL (optical axis AX, refer to FIG. 1), andreceives a reflected light of each measurement beam, thereby detectingthe position in the Y-axis direction (Y-position) of wafer table WTB atirradiation points of measurement beams B4 ₁ and B4 ₂. Incidentally, inFIG. 1, measurement beams B4 ₁ and B4 ₂ are representatively shown by ameasurement beam B4.

Further, Y interferometer 16 projects measurement beam B3 towardreflection surface 41 a along a measurement axis in the Y-axis directionspaced a predetermined distance apart in the Z-axis direction frommeasurement beams B4 ₁ and B4 ₂ between measurement beams B4 ₁ and B4 ₂,and receives measurement beam B3 reflected off reflection surface 41 a,thereby detecting the Y-position of reflection surface 41 a of movablemirror 41 (i.e. wafer stage WST).

Main controller 20 computes the Y-position (to be more accurate, adisplacement ΔY in the Y-axis direction) of reflection surface 17 a,that is, of wafer table WTB (wafer stage WST), based on the averagevalue of measurement values of measurement axes corresponding tomeasurement beams B4 ₁ and B4 ₂ of Y interferometer 16. In addition,main controller 20 computes a displacement (yawing amount) Δθz^((Y)) inthe rotation direction around the Z-axis (8 z direction) of wafer tableWTB from the difference between the measurement values of themeasurement axes corresponding to measurement beams B4 ₁ and B4 ₂.Further, main controller 20 computes a displacement (pitching amount)Δθx in the θx direction of wafer stage WST based on the Y-position (thedisplacement ΔY in the Y-axis direction) of reflection surface 17 a andreflection surface 41 a.

Further, as is shown in FIG. 2, X interferometer 126 projectsmeasurement beams B5 ₁ and B5 ₂ to wafer table WTB along the twomeasurement axes that are spaced the same distance apart from a straightline LH in the X-axis direction passing through the optical axis ofprojection optical system PL, and main controller 20 computes theposition in the X-axis direction (X-position, to be more accurate, adisplacement ΔX in the X-axis direction) of wafer table WTB, based onthe measurement values of the measurement axes corresponding tomeasurement beams B5 ₁ and B5 ₂. Further, main controller 20 computes adisplacement (yawing amount) Δθz^((X)) in the θz direction of wafertable WTB from the difference between the measurement values of themeasurement axes corresponding to measurement beams B5 ₁ and B5 ₂.Incidentally, Δθz^((X)) obtained from X interferometer 126 and θz^((Y))obtained from Y interferometer 16 are equal to each other, and theyrepresent a displacement (yawing) Δθz in the θz direction of wafer tableWTB.

Further, as is indicated by a dotted line in FIG. 2, a measurement beamB7 is emitted from X interferometer 128 along the measurement axisparallel to the X-axis. In actual, X interferometer 128 projectsmeasurement beam B7 to reflection surface 17 b of wafer table WTBlocated in the vicinity of an unloading position UP and a loadingposition LP (to be described later, refer to FIG. 3), along themeasurement axis parallel to the X-axis that connects unloading positionUP and loading position LP. Further, as is shown in FIG. 2, ameasurement beam B6 from X interferometer 127 is projected to reflectionsurface 17 b of wafer table WTB. In actual, measurement beam B6 isprojected to reflection surface 17 b of wafer table WTB, along themeasurement axis parallel to the X-axis passing through the detectioncenter of a primary alignment system AL1.

Main controller 20 can obtain the displacement ΔX in the X-axisdirection of wafer table WTB also from the measurement value ofmeasurement beam B6 of X interferometer 127 and from the measurementvalue of measurement beam B7 of X interferometer 128. However, theplacements of three X interferometers 126, 127 and 128 are different inthe Y-axis direction, and therefore, X interferometer 126 is used whenexposure is performed as shown in FIG. 14, X interferometer 127 is usedwhen wafer alignment is performed as shown in the drawings such as FIG.21, and X interferometer 128 is used when a wafer is loaded as shown inFIGS. 18 and 19 and when a wafer is unloaded as shown in FIG. 17.

Measurement beams B1 and B2 along the Y-axis are projected from each ofZ interferometers 43A and 43B toward movable mirror 41. Measurementbeams B1 and B2 are incident on reflection surfaces 41 b and 41 c ofmovable mirror 41 at a predetermined incident angle (to be θ/2),respectively. Then, measurement beams B1 and B2 are reflected offreflection surfaces 41 b and 41 c respectively, and are verticallyincident on the reflection surfaces of fixed mirrors 47A and 47B. Then,measurement beams B1 and B2 reflected off the reflections surfaces offixed mirrors 47A and 47B are again reflected off reflection surfaces 41b and 41 c respectively (i.e. return in the optical paths, through whichthe incident beams passed through, in the reversed directions), and arereceived by Z interferometers 43A and 43B.

Herein, when a displacement in the Y-axis direction of wafer stage WST(i.e. movable mirror 41) is assumed to be ΔYo and a displacement in theZ-axis direction is assumed to be ΔZo, an optical path length change ΔL1of measurement beam B1 and an optical path length change ΔL2 ofmeasurement beam B2 that are received by Z interferometers 43A and 43Bare expressed in the following equations (1) and (2), respectively.

ΔL1=ΔYo×(1+cos θ)−ΔZo×sin θ  (1)

ΔL2=ΔYo×(1+cos θ)+Δzo×sin θ  (2)

Accordingly, from the equations (1) and (2), the displacements ΔZo andΔYo are obtained by the following equations (3) and (4).

ΔZo=(ΔL2−ΔL1)/2 sin θ  (3)

ΔYo=(ΔL1+ΔL2)/{2(1+cos θ)}  (4)

The displacements ΔZo and ΔYo are obtained by each of Z interferometers43A and 43B. Then, the displacements obtained by Z interferometer 43Aare assumed to be ΔZoR and ΔYoR, and the displacements obtained by Zinterferometer 43B are assumed to be ΔZoL and ΔYoL. A distance betweenmeasurement beams B1 and B2 projected by each of Z interferometers 43Aand 43B that are apart from each other in the X-axis direction isassumed to be D (refer to FIG. 2). On such assumption, the displacement(yawing amount) Δθz in the θz direction of movable mirror 41 (i.e. waferstage WST) and the displacement (rolling amount) Δθy in the θy directionof movable mirror 41 (i.e. wafer stage WST) are obtained by thefollowing equations (5) and (6).

Δθz≈(ΔYoR−ΔYoL)/D  (5)

Δθy≈(ΔZoL−ΔZoR)/D  (6)

Accordingly, main controller 20 can compute the displacements of fourdegrees of freedom, i.e. ΔZo, ΔYo, Δθz and Δθy of wafer stage WST basedon the measurement results of Z interferometers 43A and 43B, by usingthe above-described equations (3) to (6).

In this manner, main controller 20 can obtain the displacements of waferstage WST in directions of six degrees of freedom (Z, X, Y, θz, θx andθy directions) from the measurement results of interferometer system118. Incidentally, in the embodiment, interferometer system 118 is to becapable of measuring position information of wafer stage WST in thedirections of six degrees of freedom. However, the measurementdirections are not limited to the directions of six degrees of freedom,but may also be directions of five or less degrees of freedom.

Incidentally, in the embodiment, although the case has been describedwhere wafer stage WST (91, WTB) is a single stage that is movable indirections of six degrees of freedom, the present invention is notlimited thereto. Wafer stage WST may also be configured including stagemain section 91 that is freely movable within the XY plane, and wafertable WTB that is mounted on stage main section 91 and is finelydrivable relatively to stage main section 91 in at least the Z-axisdirection, the 9 x direction and the θy direction. In this case, movablemirror 41 described above is arranged on wafer table WTB. Further,instead of reflection surfaces 17 a and 17 b, a movable mirror made upof a planar mirror may be arranged at wafer table WTB.

In the embodiment, however, position information of wafer stage WST(wafer table WTB) within the XY plane (position information indirections of three degrees of freedom including rotation information inthe Oz direction) is mainly measured by an encoder system (to bedescribed later), and the measurement values of interferometers 16, 126,127 are secondarily used in the cases such as when long-term fluctuationof the measurement values of the encoder system (e.g. due to deformationover time of the scales, or the like) is corrected (calibrated), or whenthe backup becomes necessary at the time the abnormal output of theencoder system occurs. Incidentally, in the embodiment, out of positioninformation of wafer stage WST in the directions of six degrees offreedom, position information in directions of three degrees of freedomincluding the X-axis direction, the Y-axis direction and the θzdirection is measured by the encoder system (to be described later), andposition information in directions of the remaining three degrees offreedom, that is, the Z-axis direction, the θx direction and the θydirection is measured by a measurement system (to be described later)having a plurality of Z sensors. Herein, the position information indirections of the remaining three degrees of freedom may also bemeasured by both the measurement system and interferometer system 118.For example, the position information in the Z-axis direction and the θydirection may be measured by the measurement system and the positioninformation in the θx direction may be measured by interferometer system118.

Incidentally, at least part of interferometer system 118 (such as anoptical system) may be arranged at the main frame that holds projectionunit PU, or may also be arranged integrally with projection unit PU thatis supported in a suspended state as is described above, but, in theembodiment, interferometer system 118 is to be arranged at themeasurement frame described above.

Measurement stage MST includes stage main section 92 described above anda measurement table MTB mounted on stage main section 92. Measurementtable MTB is mounted on stage main section 92 via a Z-leveling mechanism(not shown). However, the present invention is not limited to this, and,for example, measurement stage MST having a so-called coarse/fine motionstructure in which measurement table MTB is configured finely movablewith respect to stage main section 92 in the X-axis direction, theY-axis direction and the θz direction may also be employed, or theconfiguration may also be employed in which measurement table MTB isfixed on stage main section 92 and the entire measurement stage MSTincluding measurement table MTB and stage main section 92 is drivable indirections of six degrees of freedom.

Various types of measurement members are arranged at measurement tableMTB (and stage main section 92). For example, as is shown in FIGS. 2 and5A, measurement members such as an irregular illuminance sensor 94 thathas a pinhole-shaped light-receiving section that receives illuminationlight IL on an image plane of projection optical system PL, an aerialimage measuring instrument 96 that measures an aerial image (projectedimage) of a pattern that is projected by projection optical system PL,and a wavefront aberration measuring instrument 98 by the Shack-Hartmanmethod that is disclosed in, for example, the pamphlet of InternationalPublication No. WO 03/065428 and the like are employed. As wavefrontaberration measuring instrument 98, the one disclosed in, for example,the pamphlet of International Publication No. WO 99/60361 (thecorresponding EP Patent Application Publication No. 1 079 223) can alsobe used.

As irregular illuminance sensor 94, the configuration similar to the onethat is disclosed in, for example, Kokai (Japanese Unexamined PatentApplication Publication) No. 57-117238 (the corresponding U.S. Pat. No.4,465,368) and the like can be used. Further, as aerial image measuringinstrument 96, the configuration similar to the one that is disclosedin, for example, Kokai (Japanese Unexamined Patent ApplicationPublication) No. 2002-014005 (the corresponding U.S. Patent ApplicationPublication No. 2002/0041377) and the like can be used. Incidentally,three measurement members (94, 96 and 98) are to be arranged atmeasurement stage MST in the embodiment, however, the types and/or thenumber of measurement members are/is not limited to them. As themeasurement members, for example, measurement members such as atransmittance measuring instrument that measures a transmittance ofprojection optical system PL, and/or a measuring instrument thatobserves local liquid immersion unit 8, for example, nozzle unit 32 (ortip lens 191) or the like may also be used. Furthermore, membersdifferent from the measurement members such as a cleaning member thatcleans nozzle unit 32, tip lens 191 or the like may also be mounted onmeasurement stage MST.

In the embodiment, as can be seen from FIG. 5A, the sensors that arefrequently used such as irregular illuminance sensor 94 and aerial imagemeasuring instrument 96 are placed on a centerline CL (Y-axis passingthrough the center) of measurement stage MST. Therefore, in theembodiment, measurement using theses sensors can be performed by movingmeasurement stage MST only in the Y-axis direction without moving themeasurement stage in the X-axis direction.

In addition to each of the sensors described above, an illuminancemonitor that has a light-receiving section having a predetermined areasize that receives illumination light IL on the image plane ofprojection optical system PL may also be employed, which is disclosedin, for example, Kokai (Japanese Unexamined Patent ApplicationPublication) No. 11-016816 (the corresponding U.S. Patent ApplicationPublication No. 2002/0061469) and the like. The illuminance monitor isalso preferably placed on the centerline.

Incidentally, in the embodiment, liquid immersion exposure is performedin which wafer W is exposed with exposure light (illumination light) ILvia projection optical system PL and liquid (water) Lq, and accordinglyirregular illuminance sensor 94 (and the illuminance monitor), aerialimage measuring instrument 96 and wavefront aberration measuringinstrument 98 that are used in measurement using illumination light ILreceive illumination light IL via projection optical system PL and waterLq. Further, only part of each sensor such as the optical system may bemounted on measurement table MTB (and stage main section 92), or theentire sensor may be placed on measurement table MTB (and stage mainsection 92).

As is shown in FIG. 5B, a frame-shaped attachment member 42 is fixed tothe end surface on the −Y side of stage main section 92 of measurementstage MST. Further, to the end surface on the −Y side of stage mainsection 92, a pair of photodetection systems 44 are fixed in thevicinity of the center position in the X-axis direction inside anopening of attachment member 42, in the placement capable of facing apair of light-transmitting systems 36 described previously. Each ofphotodetection systems 44 is composed of an optical system such as arelay lens, a light-receiving element such as a photomultiplier tube,and a housing that houses them. As is obvious from FIGS. 4B and 5B andthe description so far, in the embodiment, in a state where wafer stageWST and measurement stage MST are closer together within a predetermineddistance in the Y-axis direction (including a contact state),illumination light IL that has been transmitted through each aerialimage measurement slit pattern SL of measurement plate 30 is guided byeach light-transmitting system 36 and received by the light-receivingelement inside each photodetection system 44. That is, measurement plate30, light-transmitting systems 36 and photodetection systems 44constitute an aerial image measuring unit 45 (refer to FIG. 6), which issimilar to the one disclosed in Kokai (Japanese Unexamined PatentApplication Publication) No. 2002-014005 (the corresponding U.S. PatentApplication Publication No. 2002/0041377) referred to previously, andthe like.

On attachment member 42, a confidential bar (hereinafter, shortlyreferred to as a “CD bar”) 46 that is made up of a bar-shaped memberhaving a rectangular sectional shape and serves as a reference member isarranged extending in the X-axis direction. CD bar 46 is kinematicallysupported on measurement stage MST by full-kinematic mount structure.

Since CD bar 46 serves as a prototype standard (measurement standard),optical glass ceramics with a low coefficient of thermal expansion, suchas Zerodur (the brand name) of Schott AG are employed as the materials.The flatness degree of the upper surface (the surface) of CD bar 46 isset high to be around the same level as a so-called datum plane plate.Further, as is shown in FIG. 5A, a reference grating (e.g. diffractiongrating) 52 whose periodic direction is the Y-axis direction isrespectively formed in the vicinity of the end portions on one side andthe other side in the longitudinal direction of CD bar 46. The pair ofreference gratings 52 are formed apart from each other at apredetermined distance (which is to be “L”) in the symmetrical placementwith respect to the center in the X-axis direction of CD bar 46, thatis, centerline CL described above.

Further, on the upper surface of CD bar 46, a plurality of referencemarks M are formed in the placement as shown in FIG. 5A. The pluralityof reference marks M are formed in three-row arrays in the Y-axisdirection in the same pitch, and the array of each row is formed beingshifted from each other by a predetermined distance in the X-axisdirection. As each of reference marks M, a two-dimensional mark having asize that can be detected by the primary alignment system and secondaryalignment systems (to be described later) is used. Reference mark M mayalso be different in shape (constitution) from fiducial mark FM, but inthe embodiment, reference mark M and fiducial mark FM have the sameconstitution and also they have the same constitution with that of analignment mark on wafer W. Incidentally, in the embodiment, the surfaceof CD bar 46 and the surface of measurement table MTB (which may includethe measurement members described above) are also covered with a liquidrepellent film (water repellent film) severally.

Also on the +Y end surface and the −X end surface of measurement tableMTB, reflection surfaces 19 a and 19 b are formed similar to wafer tableWTB as described above (refer to FIGS. 2 and 5A). By projecting aninterferometer beam (measurement beam), as is shown in FIG. 2, toreflection surfaces 19 a and 19 b and receiving a reflected light ofeach interferometer beam, Y interferometer 18 and an X interferometer130 (X interferometer 130 is not shown in FIG. 1, refer to FIG. 2) ofinterferometer system 118 (refer to FIG. 6) measure a displacement ofeach reflection surface from a datum position, that is, positioninformation of measurement stage MST (e.g. including at least positioninformation in the X-axis and Y-axis directions and rotation informationin the θz direction), and the measurement values are supplied to maincontroller 20.

In exposure apparatus 100 of the embodiment, in actual, primaryalignment system AL1 is placed on straight line LV passing through thecenter of projection unit PU (optical axis AX of projection opticalsystem PL, which also coincides with the center of exposure area IA inthe embodiment) and being parallel to the Y-axis, and has a detectioncenter at a position that is spaced apart from the optical axis at apredetermined distance on the −Y side as is shown in FIG. 3, althoughomitted in FIG. 1 from the viewpoint of avoiding intricacy of thedrawing. Primary alignment system AL1 is fixed to the lower surface of amain frame (not shown) via a support member 54. On one side and theother side in the X-axis direction with primary alignment system AL1 inbetween, secondary alignment systems AL2 ₁ and AL2 ₂, and AL2 ₃ and AL2₄ whose detection centers are substantially symmetrically placed withrespect to straight line LV are respectively arranged. That is, fivealignment systems AL1 and AL2 ₁ to AL2 ₄ are placed so that theirdetection centers are placed at different positions in the X-axisdirection, that is, placed along the X-axis direction.

As is representatively shown by secondary alignment system AL2 ₄, eachsecondary alignment system AL2 _(n) (n=1 to 4) is fixed to a tip(turning end) of an arm 56 n (n=1 to 4) that can turn around a rotationcenter O as the center in a predetermined angle range in clockwise andanticlockwise directions in FIG. 3. In the embodiment, a partial sectionof each secondary alignment system AL2 _(n) (e.g. including at least anoptical system that irradiates an alignment light to a detection areaand also leads the light that is generated from a subject mark withinthe detection area to a light-receiving element) is fixed to arm 56 _(n)and the remaining section is arranged at the main frame that holdsprojection unit PU. The X-positions of secondary alignment systems AL2₁, AL2 ₂, AL2 ₃ and AL2 ₄ are severally adjusted by turning aroundrotation center O as the center. In other words, the detection areas (orthe detection centers) of secondary alignment systems AL2 ₁, AL2 ₂, AL2₃ and AL2 ₄ are independently movable in the X-axis direction.Accordingly, the relative positions of the detection areas of primaryalignment system AL1 and secondary alignment systems AL2 ₁, AL2 ₂, AL2 ₃and AL2 ₄ are adjustable in the X-axis direction. Incidentally, in theembodiment, the X-positions of secondary alignment systems AL2 ₁, AL2 ₂,AL2 ₃ and AL2 ₄ are to be adjusted by the turning of the arms. However,the present invention is not limited to this, and a drive mechanism thatdrives secondary alignment systems AL2 ₁, AL2 ₂, AL2 ₃ and AL2 ₄ backand forth in the X-axis direction may also be arranged. Further, atleast one of secondary alignment systems AL2 ₁, AL2 ₂, AL2 ₃ and AL2 ₄may be movable not only in the X-axis direction but also in the Y-axisdirection. Incidentally, since part of each secondary alignment systemAL2 n is moved by arm 56 n, position information of the part that isfixed to arm 56 _(n) is measurable by a sensor (not shown) such as aninterferometer, or an encoder. The sensor may only measure positioninformation in the X-axis direction of secondary alignment system AL2 n,or may be capable of measuring position information in anotherdirection, for example, the Y-axis direction and/or the rotationdirection (including at least one of the θx and θy directions).

On the upper surface of each arm 56 n, a vacuum pad 58 n (n=1 to 4) thatis composed of a differential evacuation type air bearing is arranged.Further, arm 56 n can be turned by a rotation drive mechanism 60, (n=1to 4, not shown in FIG. 3, refer to FIG. 6) that includes, for example,a motor or the like, in response to instructions of main controller 20.Main controller 20 activates each vacuum pad 58 n to fix each arm 56 nto a main frame (not shown) by suction after rotation adjustment of arm56 _(n). Thus, the state of each arm 56 n after rotation angleadjustment, that is, a desired positional relation between primaryalignment system AL1 and four secondary alignment systems AL2 ₁ to AL2 ₄is maintained.

Incidentally, in the case a portion of the main frame facing arm 56 _(n)is a magnetic body, an electromagnet may also be employed instead ofvacuum pad 58.

In the embodiment, as each of primary alignment system AL1 and foursecondary alignment systems AL2 ₁ to AL2 ₄, for example, an FIA (FieldImage Alignment) system by an image processing method is used thatirradiates a broadband detection beam that does not expose resist on awafer to a subject mark, and picks up an image of the subject markformed on a light-receiving plane by the reflected light from thesubject mark and an image of an index (an index pattern on an indexplate arranged within each alignment system, not shown), using animaging device (such as CCD), and then outputs their imaging signals.The imaging signal from each of primary alignment system AL1 and foursecondary alignment systems AL2 ₁ to AL2 ₄ is supplied to maincontroller 20 in FIG. 6.

Incidentally, each of the alignment systems described above is notlimited to the FIA system, and an alignment sensor, which irradiates acoherent detection light to a subject mark and detects a scattered lightor a diffracted light generated from the subject mark or makes twodiffracted lights (e.g. diffracted lights of the same order ordiffracted lights being diffracted in the same direction) generated fromthe subject mark interfere and detects an interference light, cannaturally be used alone or in combination as needed. Further, fivealignment systems AL1 and AL2 ₁ to AL2 ₄ are to be arranged in theembodiment. However, the number of alignment systems is not limited tofive, but may be the number equal to or more than two and equal to orless than four, or may be the number equal to or more than six, or maybe the even number, not the odd number. Moreover, in the embodiment,five alignment systems AL1 and AL2 ₁ to AL2 ₄ are to be fixed to thelower surface of the main frame that holds projection unit PU, viasupport member 54. However, the present invention is not limited tothis, and for example, the five alignment systems may also be arrangedon the measurement frame described earlier. Further, alignment systemsAL1 and AL2 ₁ to AL2 ₄ are simply called mark detection systems in theembodiment, since alignment systems AL1 and AL2 ₁ to AL2 ₄ detectalignment marks on wafer W and the reference marks on CD bar 46.

In exposure apparatus 100 of the embodiment, as is shown in FIG. 3, fourhead units 62A to 62D of the encoder system are placed in a state ofsurrounding nozzle unit 32 on all four sides. In actual, head units 62Ato 62D are fixed to the foregoing main frame that holds projection unitPU in a suspended state via a support member, although omitted in FIG. 3from the viewpoint of avoiding intricacy of the drawing. Incidentally,for example, in the case projection unit PU is supported in a suspendedstate, head units 62A to 62D may be supported in a suspended stateintegrally with projection unit PU, or may be arranged at themeasurement frame described above.

Head units 62A and 62C are respectively placed on the +X side and −Xside of projection unit PU having the longitudinal direction in theX-axis direction, and are also placed apart at the substantially samedistance from optical axis AX of projection optical system PLsymmetrically with respect to optical axis AX of projection opticalsystem PL. Further, head units 62B and 62D are respectively placed onthe +Y side and −Y side of projection unit PU having the longitudinaldirection in the Y-axis direction and are also placed apart at thesubstantially same distance from optical axis AX of projection opticalsystem PL.

As is shown in FIG. 3, head units 62A and 62C are each equipped with aplurality of (six in this case) Y heads 64 that are placed at apredetermined distance on a straight line LH that passes through opticalaxis AX of projection optical system PL and is parallel to the X-axis,along the X-axis direction. Head unit 62A constitutes a multiple-lens(six-lens, in this case) Y linear encoder (hereinafter, shortly referredto as a “Y encoder” or an “encoder” as needed) 70A (refer to FIG. 6)that measures the position in the Y-axis direction (the Y-position) ofwafer stage WST (wafer table WTB) using Y scale 39Y₁ described above.Similarly, head unit 62C constitutes a multiple-lens (six-lens, in thiscase) Y linear encoder 70C (refer to FIG. 6) that measures theY-position of wafer stage WST (wafer table WTB) using Y scale 39Y₂described above. In this case, a distance between adjacent Y heads 64(i.e. measurement beams) equipped in head units 62A and 62C is setshorter than a width in the X-axis direction of Y scales 39Y₁ and 39Y₂(to be more accurate, a length of grating line 38). Further, out of aplurality of Y heads 64 that are equipped in each of head units 62A and62C, Y head 64 located innermost is fixed to the lower end portion ofbarrel 40 of projection optical system PL (to be more accurate, to theside of nozzle unit 32 enclosing tip lens 191) so as to be placed asclose as possible to the optical axis of projection optical system PL.

As is shown in FIG. 3, head unit 62B is equipped with a plurality of(seven in this case) X heads 66 that are placed on straight line LV at apredetermined distance along the Y-axis direction. Further, head unit62D is equipped with a plurality of (eleven in this case, out of elevenX heads, however, three X heads that overlap primary alignment systemAL1 are not shown in FIG. 3) X heads 66 that are placed on straight lineLV at a predetermined distance. Head unit 62B constitutes amultiple-lens (seven-lens, in this case) X linear encoder (hereinafter,shortly referred to as an “X encoder” or an “encoder” as needed) 70B(refer to FIG. 6) that measures the position in the X-axis direction(the X-position) of wafer stage WST (wafer table WTB) using X scale 39X₁described above. Further, head unit 62D constitutes a multiple-lens(eleven-lens, in this case) X linear encoder 70D (refer to FIG. 6) thatmeasures the X-position of wafer stage WST (wafer table WTB) using Xscale 39X₂ described above. Further, in the embodiment, for example,when alignment (to be described later) or the like is performed, two Xheads 66 out of eleven X heads 66 that are equipped in head unit 62Dsimultaneously face X scale 39X₁ and X scale 39X₂ respectively in somecases. In these cases, X scale 39X₁ and x head 66 facing X scale 39X₁constitute X linear encoder 70B, and X scale 39X₂ and X head 66 facing Xscale 39X₂ constitute X linear encoder 70D.

Herein, some of eleven X heads 66, in this case, three X heads areattached on the lower surface side of support member 54 of primaryalignment system AL1. Further, a distance between adjacent X heads 66(i.e. measurement beams) that are equipped in each of head units 62B and62D is set shorter than a width in the Y-axis direction of X scales 39X₁and 39X₂ (to be more accurate, a length of grating line 37). Further, Xhead 66 located innermost out of a plurality of X heads 66 that areequipped in each of head units 62B and 62D is fixed to the lower endportion of the barrel of projection optical system PL (to be moreaccurate, to the side of nozzle unit 32 enclosing tip lens 191) so as tobe placed as close as possible to the optical axis of projection opticalsystem PL.

Moreover, on the −X side of secondary alignment system AL2 ₁ and on the+X side of secondary alignment system AL2 ₄, Y heads 64 y ₁ and 64 y ₂are respectively arranged, whose detection points are placed on astraight line parallel to the X-axis that passes through the detectioncenter of primary alignment system AL1 and are substantiallysymmetrically placed with respect to the detection center. The distancebetween Y heads 64 y ₁ and 64 y ₂ is set substantially equal to distanceL described previously. Y heads 64 y ₁ and 64 y ₂ face Y scales 39Y₂ and39Y₁ respectively in a state shown in FIG. 3 where the center of wafer Won wafer stage WST is on straight line LV. On an alignment operation (tobe described later) or the like, Y scales 39Y₂ and 39Y₁ are placedfacing Y heads 64 y ₁ and 64 y ₂ respectively, and the Y-position (andthe θz rotation) of wafer stage WST is measured by Y heads 64 y ₁ and 64y ₂ (i.e. Y encoders 70C and 70A composed of Y heads 64 y ₁ and 64 y ₂).

Further, in the embodiment, when baseline measurement of the secondaryalignment systems (to be described later) or the like is performed, apair of reference gratings 52 of CD bar 46 face Y heads 64 y ₁ and 64 y₂ respectively, and the Y-position of CD bar 46 is measured at theposition of each of reference gratings 52 by Y heads 64 y ₁ and 64 y ₂and facing reference gratings 52. In the following description, encodersthat are composed of Y heads 64 y ₁ and 64 y ₂ facing reference gratings52 respectively are referred to as Y-axis linear encoders 70E and 70F(refer to FIG. 6).

Six linear encoders 70A to 70F measure position information of waferstage WST in the respective measurement directions at a resolution of,for example, around 0.1 nm, and their measurement values (measurementinformation) are supplied to main controller 20. Main controller 20controls the position within the XY plane of wafer table WTB based onthe measurement values of linear encoders 70A to 70D, and also controlsthe rotation in the θz direction of CD bar 46 based on the measurementvalues of linear encoders 70E and 70F. Incidentally, the configurationof the linear encoders and the like will be further described later.

In exposure apparatus 100 of the embodiment, a position measurement unitthat measures position information of wafer W in the Z-axis direction isarranged. In the embodiment, as the position measurement unit, as isshown in FIG. 3, a multipoint focal position detection system(hereinafter, shortly referred to as a “multipoint AF system”) by anoblique incident method is arranged, which is composed of an irradiationsystem 90 a and a photodetection system 90 b, and has the configurationsimilar to the one disclosed in, for example, Kokai (Japanese UnexaminedPatent Application Publication) No. 06-283403 (the corresponding U.S.Pat. No. 5,448,332) and the like. In the embodiment, as an example,irradiation system 90 a is placed on the −Y side of the −X end portionof head unit 62C and photodetection system 90 b is placed on the −Y sideof the +X end portion of head unit 62A in a state of opposingirradiation system 90 a.

A plurality of detection points of the multipoint AF system (90 a, 90 b)are placed at a predetermined distance along the X-axis direction on thesurface to be detected, though omitted in the drawing. In theembodiment, the plurality of detection points are placed, for example,in the matrix arrangement having one row and M columns (M is a totalnumber of detection points) or having two rows and N columns (N is ahalf of a total number of detection points). In FIG. 3, the plurality ofdetection points to which a detection beam is severally irradiated arenot individually shown, but are shown as an elongate detection area(beam area) AF that extends in the X-axis direction between irradiationsystem 90 a and photodetection system 90 b. Since the length ofdetection area AF in the X-axis direction is set to around the same asthe diameter of wafer W, position information (surface positioninformation) in the Z-axis direction across the entire surface of waferW can be measured by only scanning wafer W in the Y-axis direction once.Further, since detection area AF is placed between liquid immersion area14 (exposure area IA) and the detection areas of the alignment systems(AL1, AL2 ₁, AL2 ₂, AL2 ₃ and AL2 ₄) in the Y-axis direction, thedetection operations of the multipoint AF system and the alignmentsystems can be performed in parallel. The multipoint AF system may alsobe arranged on the main frame that holds projection unit PU or the like,but is to be arranged on the measurement frame described earlier in theembodiment.

Incidentally, the plurality of detection points are to be placed in onerow and M columns, or two rows and N columns, but the number(s) of rowsand/or columns is/are not limited to these numbers. However, in the casethe number of rows is two or more, the positions in the X-axis directionof detection points are preferably made to be different even between thedifferent rows. Moreover, the plurality of detection points are to beplaced along the X-axis direction. However, the present invention is notlimited to this, and all of or some of the plurality of detection pointsmay also be placed at different positions in the Y-axis direction. Forexample, the plurality of detection points may also be placed along adirection that intersects both of the X-axis and the Y-axis. That is,the positions of the plurality of detection points only have to bedifferent at least in the X-axis direction. Further, a detection beam isto be irradiated to the plurality of detection points in the embodiment,but a detection beam may also be irradiated to, for example, the entirearea of detection area AF. Furthermore, the length of detection area AFin the X-axis direction does not have to be nearly the same as thediameter of wafer W.

In the embodiment, in the vicinity of detection points located at bothends out of a plurality of detection points of the multipoint AF system,that is, in the vicinity of both end portions of beam area AF, one eachpair of surface position sensors for Z position measurement(hereinafter, shortly referred to as “Z sensors”), that is, a pair of Zsensors 72 a and 72 b and a pair of Z sensors 72 c and 72 d are arrangedin the symmetrical placement with respect to straight line LV. Z sensors72 a to 72 d are fixed to the lower surface of a main frame (not shown).As Z sensors 72 a to 72 d, a sensor that irradiates a light to wafertable WTB from above, receives the reflected light and measures positioninformation of the wafer table WTB surface in the Z-axis directionorthogonal to the XY plane at an irradiation point of the light, as anexample, an optical displacement sensor (sensor by an optical pickupmethod), which has the configuration like an optical pickup used in a CDdrive unit, is used. Incidentally, Z sensors 72 a to 72 d may also bearranged on the measurement frame described above or the like.

Moreover, head unit 62C is equipped with a plurality of (six each,twelve in total, in this case) Z sensors 74 _(ij) (i=1, 2, j=1, 2, . . ., 6) that are placed at a predetermined distance so as to correspond toeach other, along each of two straight lines that are located on oneside and the other side having straight line LH in between in the X-axisdirection that connects a plurality of Y heads 64 and are parallel tostraight line LH. In this case, Z sensors 74 _(1j) and 74 _(2j) making apair are placed symmetrically with respect to straight line LH.Furthermore, plural pairs (six pairs in this case) of Z sensors 74 _(1j)and 74 _(2j) and a plurality of Y heads 64 are placed alternately in theX-axis direction. As each Z sensor 74 _(ij), for example, a sensor by anoptical pickup method similar to Z sensors 72 a to 72 d is used.

Herein, a distance between Z sensors 74 _(1j) and 74 _(2j) in each pairthat are located symmetrically with respect to straight line LH is setto be the same distance as a distance between Z sensors 72 a and 72 b.Further, a pair of Z sensors 74 _(1,4) and 74 _(2,4) are located on thesame straight line in the Y-axis direction as Z sensors 72 a and 72 b.

Further, head unit 62A is equipped with a plurality of (twelve in thiscase) Z sensors 76, (p=1, 2 and q=1, 2, . . . , 6) that are placedsymmetrically to a plurality of Z sensors 74 _(ij) with respect tostraight line LV. As each Z sensor 76 _(pq), a sensor by an opticalpickup method similar to Z sensors 72 a to 72 d is used. Further, a pairof Z sensors 76 _(1,3) and 76 _(2,3) are located on the same straightline in the Y-axis direction as Z sensors 72 c and 72 d. Incidentally, Zsensors 74 _(ij) and 76 _(pq) are arranged at, for example, the mainframe or the measurement frame described above. Further, in theembodiment, the measurement system having Z sensors 72 a to 72 d, 74_(ij) and 76 _(pq) measures position information in the Z-axis directionof wafer stage WST using one or a plurality of Z sensor(s) that face(s)the scale(s) described above. Therefore, in the exposure operation, Zsensors 74 _(ij) and 76 _(pq) to be used for position measurement areswitched according to movement of wafer stage WST. Further, in theexposure operation, Y scale 39Y₁ and at least one Z sensor 76 _(pq) faceeach other, and Y scale 39Y₂ and at least one Z sensor 74 _(ij) faceeach other. Accordingly, the measurement system can measure not onlyposition information in the Z-axis direction of wafer stage WST but alsoposition information (rolling) in the θy direction of wafer stage WST.Further, in the embodiment, each Z sensor of the measurement system isto detect a grating surface (a formation surface of diffractiongratings), but each Z sensor may also detect a surface different fromthe grating surface, for example, a surface of a cover glass that coversthe grating surface.

Incidentally, in FIG. 3, measurement stage MST is omitted and a liquidimmersion area that is formed by water Lq held in the space betweenmeasurement stage MST and tip lens 191 is denoted by a reference code14. Further, in FIG. 3, a reference code 78 denotes a localair-conditioning system that blows dry air whose temperature is adjustedto a predetermined temperature to the vicinity of a beam path of themultipoint AF system (90 a, 90 b) by, for example, downflow as isindicated by outline arrows in FIG. 3. Further, a reference code UPdenotes an unloading position where a wafer on wafer table WTB isunloaded, and a reference code LP denotes a loading position where awafer is loaded on wafer table WTB. In the embodiment, unloadingposition UP and loading position LP are set symmetrically with respectto straight line LV. Incidentally, unloading position UP and loadingposition LP may be the same position.

FIG. 6 shows the main configuration of the control system of exposureapparatus 100. The control system is mainly configured of maincontroller 20 composed of a microcomputer (or workstation) that performsoverall control of the entire apparatus. Correction information (to bedescribed later) is stored in a memory 34 that is an external storageunit connected to main controller 20. Incidentally, in FIG. 6, varioussensors such as irregular illuminance sensor 94, aerial image measuringinstrument 96 and wavefront aberration measuring instrument 98 that arearranged at measurement stage MST are collectively shown as a sensorgroup 99.

In exposure apparatus 100 of the embodiment having the configurationdescribed above, since the placement of X scales and Y scales on wafertable WTB as described above and the placement of X heads and Y heads asdescribed above are employed, at least one X head 66 out of a total of18 X heads that belong to head units 62B and 62D faces at least eitherone of X scale 39X₁ or 39X₂, and at least one each of Y head 64 thatrespectively belongs to head units 62A and 62C or Y heads 64 y ₁ and 64y ₂ face Y scales 39Y₁ and 39Y₂ respectively without fail in aneffective stroke range of wafer stage WST (i.e. a range in which waferstage WST moves for the alignment and the exposure operation, in theembodiment), as is exemplified in the drawings such as FIGS. 7A and 7B.That is, at least one each of corresponding heads faces at least threeof the four scales.

Incidentally, in FIGS. 7A and 7B, the heads that face the correspondingX scales or Y scales are indicated by being circled.

Therefore, in the effective stroke range of wafer stage WST describedabove, main controller 20 can control position information (includingrotation information in the 8 z direction) of wafer stage WST within theXY plane with high precision by controlling each motor constitutingstage drive system 124, based on measurement values of at least threeencoders in total, which are encoders 70A and 70C, and at least eitherone of encoder 70B or 70D. Since the influence of air fluctuations thatthe measurement values of encoders 70A to 70D receive is small enough tobe ignored when comparing with the interferometer, the short-termstability of the measurement values that is affected by air fluctuationsis remarkably better than that of the interferometer.

Further, when wafer stage WST is driven in the X-axis direction asindicated by an outline arrow in FIG. 7A, Y head 64 that measures theposition in the Y-axis direction of wafer stage WST is sequentiallyswitched to adjacent Y head 64 as indicated by arrows e₁ and e₂ in thedrawing. For example, Y head 64 circled by a solid line is switched to Yhead 64 circled by a dotted line. Therefore, a linkage process of themeasurement values is performed before and after the switching. In otherwords, in the embodiment, in order to perform the switching of Y heads64 and the linkage process of the measurement values smoothly, adistance between adjacent Y heads 64 that are equipped in head units 62Aand 62C is set shorter than a width of Y scales 39Y₁ and 39Y₂ in theX-axis direction, as is described previously.

Further, in the embodiment, since a distance between adjacent X heads 66that are equipped in head units 62B and 62D is set shorter than a widthof X scales 39X₁ and 39X₂ in the Y-axis direction as is describedpreviously, when wafer stage WST is driven in the Y-axis direction asindicated by an outline arrow in FIG. 7B, X head 66 that measures theposition in the X-axis direction of wafer stage WST is sequentiallyswitched to adjacent X head 66 (e.g. X head 66 circled by a solid lineis switched to X head 66 circled by a dotted line), and the linkageprocess of the measurement values is performed before and after theswitching.

Next, the configuration of encoders 70A to 70F, and the like will bedescribed, focusing on Y encoder 70A that is enlargedly shown in FIG.8A, as a representative. FIG. 8A shows one Y head 64 of head unit 62Athat irradiates a detection light (measurement beam) to Y scale 39Y₁.

Y head 64 is mainly composed of three sections, which are an irradiationsystem 64 a, an optical system 64 b and a photodetection system 64 c.

Irradiation system 64 a includes a light source that emits a laser beamLB in a direction inclined at an angel of 45 degrees with respect to theY-axis and Z-axis, for example, a semiconductor laser LD, and aconverging lens L1 that is placed on the optical path of laser beam LBemitted from semiconductor laser LD.

Optical system 64 b is equipped with a polarization beam splitter PBSwhose separation plane is parallel to an XZ plane, a pair of reflectionmirrors Rla and Rlb, lenses L2 a and L2 b, quarter wavelength plates(hereinafter, referred to as λ/4 plates) WP1 a and WP1 b, reflectionmirrors R2 a and R2 b, and the like.

Photodetection system 64 c includes a polarizer (analyzer), aphotodetector, and the like.

In Y encoder 70A, laser beam LB emitted from semiconductor laser LD isincident on polarization beam splitter PBS via lens L1, and is split bypolarization into two beams LB₁ and LB₂. Beam LB₁ having beentransmitted through polarization beam splitter PBS reaches reflectivediffraction grating RG that is formed on Y scale 39Y₁, via reflectionmirror R1 a, and beam LB₂ reflected off polarization beam splitter PBSreaches reflective diffraction grating RG via reflection mirror R1 b.Incidentally, “split by polarization” in this case means the splittingof an incident beam into a P-polarization component and anS-polarization component.

Predetermined-order diffracted beams that are generated from diffractiongrating RG due to irradiation of beams LB₁ and LB₂, for example, thefirst-order diffracted beams are severally converted into a circularpolarized light by λ/4 plates WP1 b and WP1 a via lenses L2 b and L2 a,and reflected by reflection mirrors R2 b and R2 a and then the beamspass through λ/4 plates WP1 b and WP1 a again and reach polarizationbeam splitter PBS by tracing the same optical path in the reverseddirection.

Each of the polarization directions of the two beams that have reachedpolarization beam splitter PBS is rotated at an angle of 90 degrees withrespect to the original direction. Therefore, the first-order diffractedbeam of beam LB₁ that was previously transmitted through polarizationbeam splitter PBS is reflected off polarization beam splitter PBS and isincident on photodetection system 64 c, and also the first-orderdiffracted beam of beam LB₂ that was previously reflected offpolarization beam splitter PBS is transmitted through polarization beamsplitter PBS and is synthesized concentrically with the first-orderdiffracted beam of beam LB₁ and is incident on photodetection system 64c.

Then, the polarization directions of the two first-order diffractedbeams described above are uniformly arranged by the analyzer insidephotodetection system 64 c and the beams interfere with each other to bean interference light, and the interference light is detected by thephotodetector and is converted into an electric signal in accordancewith the intensity of the interference light.

As is obvious from the above description, in Y encoder 70A, since theoptical path lengths of two beams to be interfered are extremely shortand also are almost equal to each other, the influence by airfluctuations can mostly be ignored. Then, when Y scale 39Y₁ (i.e. waferstage WST) moves in the measurement direction (the Y-axis direction, inthis case), the phase of each of the two beams changes and thus theintensity of the interference light changes. This change in theintensity of the interference light is detected by photodetection system64 c, and position information in accordance with the intensity changeis output as the measurement value of Y encoder 70A. Other encoders 70B,70C, 70D and the like are also configured similar to encoder 70A.

Meanwhile, when wafer stage WST moves in a direction different from theY-axis direction and a relative motion in a direction other than thedirection to be measured (relative motion in a non-measurementdirection) is generated between head 64 and Y scale 39Y₁, a measurementerror occurs in Y encoder 70A due to the relative motion in most cases.A mechanism of this measurement error occurrence will be describedbelow.

First of all, a relation between the intensity of an interference lightthat is synthesized from two returning beams LB₁ and LB₂ and adisplacement (a relative displacement with Y head 64) of Y scales 39Y₂(reflective diffraction grating RG) is derived.

In FIG. 8B, beam LB₁ reflected off reflection mirror R1 a is incident onreflective diffraction grating RG at an angle of θ_(a0), and the n_(a)^(th)-order diffracted light is assumed to be generated at an angle ofθ_(a1). Then, a returning beam that is reflected off reflection mirrorR2 a and traces the back route is incident on reflective diffractiongrating RG at an angle of θ_(a1). Then, a diffracted light is generatedagain. Herein, the diffracted light that is generated at an angle ofθ_(a0) and proceeds to reflection mirror R1 a by tracing the originaloptical path is the n_(a) ^(th)-order diffracted light that is the sameorder as the diffracted light generated in the approach route.

On the other hand, beam LB₂ reflected off reflection mirror R1 _(b) isincident on reflective diffraction grating RG at an angle of θ_(b0), andthe n_(b) ^(th)-order diffracted light is generated at an angle ofθ_(b1). This diffracted light is assumed to be reflected off reflectionmirror R2 b and trace the same optical path to return to reflectionmirror R1 b.

In this case, the intensity “I” of an interference light that issynthesized from two returning beams LB₁ and LB₂ depends on a differencein phase (phase difference) φ between two returning beams LB₁ and LB₂ ata photodetection position of the photodetector, that is, I∝1+cos φ. Inthis case, the intensities of two returning beams LB₁ and LB₂ are assumeto be equal to each other.

Phase difference φ can theoretically be calculated in the followingequation (7), though the way to derive phase difference φ in detail isomitted herein.

φ=KΔL+4π(n _(b) −n _(a))ΔY/p+2KΔZ(cos θ_(b1)+cos θ_(b0)−cos θ_(a1)−cosθ_(a1))  (7)

In this case, KΔL denotes a phase difference caused by an optical pathdifference ΔL between two returning beams LB₁ and LB₂, ΔY denotes adisplacement of reflective diffraction grating RG in the +Y direction,ΔZ denotes a displacement of reflective diffraction grating RG in the +Zdirection, p denotes a pitch of a diffraction grating, and n_(b) orn_(a) denotes the diffraction order of each diffracted light describedabove.

Herein, the encoder is assumed to be configured so as to satisfy theoptical path difference ΔL=0 and the symmetric property shown by thefollowing equation (8).

θ_(a0)=θ_(b0), θ_(a1)=θ_(b1)  (8)

In such a case, a result in the parenthesis in the third term on theright-hand side of the equation (7) becomes zero, and at the same timeN_(b)=−n_(a) (=n) is satisfied, and accordingly, the following equation(9) can be obtained.

φ_(sym)(ΔY)=2πΔY/(p/4n)  (9)

From the above equation (9), phase difference φ_(sym) does not depend onthe wavelength of light.

Herein, two cases shown in FIGS. 9A and 9B will be considered, as simpleexamples. First, in the case of FIG. 9A, an optical path of head 64coincides with the Z-axis direction (head 64 does not incline). Herein,wafer stage WST is assumed to be displaced in the Z-axis direction(ΔZ≠0, ΔY=0). In this case, since optical path difference ΔL does notchange, the first term on the right-hand side of the equation (7) doesnot change. The second term becomes zero because of the assumption:ΔY=0. Then, the third term becomes zero, because the symmetric propertyin the equation (8) is satisfied. Accordingly, phase difference φ doesnot change, and also the intensity of the interference light does notchange. As a consequence, the measurement value (count value) of theencoder does not change.

On the other hand, in the case of FIG. 9B, the optical path of head 64inclines with respect to the Z-axis (head 64 inclines). Wafer stage WSTis assumed to be displaced in the Z-axis direction from this state(ΔZ≠0, ΔY=0). Also in this case, since optical path difference ΔL doesnot change, the first term on the right-hand side of the equation (7)does not change. The second term becomes zero because of the assumption:ΔY=0. However, the third term does not become zero, because thesymmetric property in the equation (8) is not kept due to the gradientof the head, and the third term changes in proportion to a Zdisplacement ΔZ. Accordingly, phase difference φ changes, and as aconsequence, the measurement value changes. Incidentally, even when head64 does not incline, the symmetric property in the equation (8) is notkept due to, for example, the optical characteristics of the head (suchas telecentricity), and the measurement value changes similarly. Thatis, characteristic information of the head units that is a factorcausing measurement errors of the encoder system includes not only thegradient of the heads but also the optical characteristics of the headsand the like.

Further, although omitted in the drawing, in the case wafer stage WST isdisplaced in a direction perpendicular to the measurement direction(Y-axis direction) and to the optical axis direction (Z-axis direction)(ΔX≠0, ΔY=0, ΔZ=0), the measurement value does not change as far as adirection in which grating lines of diffraction grating RG face (alongitudinal direction) is orthogonal to the measurement direction. Inthe case the longitudinal direction is not orthogonal to the measurementdirection, however, the sensitivity is generated at the gain that isproportionate to the angle.

Next, for example, the four cases shown in FIGS. 10A to 10D will beconsidered. First, in the case of FIG. 10A, the optical path of head 64coincides with the Z-axis direction (head 64 does not incline). Evenwhen wafer stage WST moves in the +Z direction from this state to gointo a state in FIG. 10B, the measurement value of the encoder does notchange because this is the same as the case of FIG. 9A described above.

Next, wafer stage WST is assumed to rotate around the X-axis from thestate in FIG. 10B to go into a state shown in FIG. 10C. In this case,although the relative motion between the head and the scale does notoccur, that is, regardless of ΔY=ΔZ=0, the measurement value of theencoder changes, since optical path difference ΔL changes due to therotation of wafer stage WST. That is, the measurement error occurs inthe encoder system due to the inclination (tilt) of wafer stage WST.

Next, wafer stage WST is assumed to move downward from the state in FIG.10C to go into a state as shown in FIG. 10D. In this case, optical pathdifference ΔL does not change since wafer stage WST does not rotate.However, because the symmetric property in the equation (8) is not kept,phase difference p changes due to the Z displacement ΔZ by the thirdterm on the right-hand side of the equation (7). Accordingly, themeasurement value of the encoder changes. Incidentally, the measurementvalue of the encoder in the case of FIG. 10D becomes the same value inthe case of FIG. 10A.

As a result of the simulation implemented by the inventor and the like,it was found that the measurement values of the encoder have thesensitivity with respect to not only the positional change of the scalein the Y-axis direction, which is the measurement direction, but alsothe attitude change in the θx direction (pitching direction) and the θzdirection (yawing direction), and besides, in the cases such as when thesymmetric property described above is broken, the measurement valuesdepend also on the positional change in the Z-axis direction. That is,the theoretical explanation described above and the result of thesimulation agree.

Thus, in the embodiment, correction information for correcting themeasurement error of each encoder caused by the relative motion of thehead and the scale in the non-measurement direction described above isacquired in the manner described below.

a. First of all, main controller 20 drives wafer stage WST via stagedrive system 124 while monitoring the measurement values of Yinterferometer 16, X interferometer 126 and Z interferometers 43A and43B of interferometer system 118, and makes Y head 64 located on themost −X side of head unit 62A face an arbitrary area (an area indicatedby being circled in FIG. 11A) AR of Y scale 39Y₁ on the upper surface ofwafer table WTB, as is shown in FIGS. 11A and 11B.

b. Then, based on the measurement values of Y interferometer 16 and Zinterferometers 43A and 43B, main controller 20 drives wafer table WTB(wafer stage WST) so that both the rolling amount θy and the yawingamount θz of wafer table WTB (wafer stage WST) become zero and also thepitching amount θx becomes a desired value α₀ (in this case, α₀ isassumed to be equal to 200 μrad). After the driving of wafer table WTB(wafer stage WST), main controller 20 irradiates a detection light fromthe head 64 described above to area AR of Y scale 39Y₁, and stores themeasurement value, which corresponds to a photoelectric conversionsignal from the head 64 that has received the reflected light, in aninternal memory.

c. Next, based on the measurement values of Y interferometer 16 and zinterferometers 43A and 43B, main controller 20 drives wafer table WTB(wafer stage WST) in the Z-axis direction in a predetermined range, forexample, a range of −100 μm to +100 μm as is indicated by an arrow inFIG. 11B while maintaining an attitude of wafer table WTB (wafer stageWST) (the pitching amount θx=α₀, the yawing amount θz=0, the rollingamount θy=0) of wafer table WTB (wafer stage WST), and during thedriving, while irradiating a detection light from the Y head 64described above to area AR of Y scale 39Y₁, main controller 20sequentially loads the measurement value corresponding to aphotoelectric conversion signal from the head 64 that has received thereflected light at predetermined sampling intervals, and stores them inan internal memory.

d. Next, main controller 20 changes the pitching amount of wafer tableWTB (wafer stage WST) to (θx=α₀−Δα) based on the measurement value of Yinterferometer 16.

e. Subsequently, the similar operation to the operation in the above c.is repeated with the changed attitude.

f. After that, main controller 20 repeats the operations in the above d.and e. alternately, and loads the measurement value of head 64 in arange of the above-described Z-driving range at Δα(rad) intervals, forexample, 40 μrad intervals, with respect to the range in which thepitching amount θx is −200 μrad<θx<+200 μrad.

g. Next, by plotting the respective data within the internal memory thathave been obtained by the processes of the above b. to e. on atwo-dimensional coordinate system that has a horizontal axis showing Zpositions and a vertical axis showing encoder measurement values, andsequentially connecting plot points at which the pitching amount is thesame, and then shifting the horizontal axis in the vertical axisdirection so that a line (a horizontal line in the center) that connectsthe plot points at which the pitching amount is zero passes through theorigin, a graph as shown in FIG. 12 is obtained.

The value of each point in the vertical axis in the graph in FIG. 12 isa measurement error of the encoder at each Z position in the case wherethe pitching amount ex equals a (θx=α). Then, main controller 20 assumesthe pitching amount θx, the Z-position, the encoder measurement error ateach point in the graph of FIG. 12 as table data, and stores the tabledata in a memory 34 (refer to FIG. 6) as correction information. Or,main controller 20 assumes the measurement error as the mathematicalfunction of a Z-position z and the pitching amount θx, obtains themathematical function by computing undetermined coefficients using, forexample, the least-squares method, and stores the mathematical functionas correction information in memory 34.

h. Next, main controller 20 drives wafer stage WST via stage drivesystem 124 in the −X direction a predetermined distance while monitoringthe measurement values of X interferometer 126 of interferometer system118, and as is shown in FIG. 13, makes Y head 64 that is located in thesecond position from the −X side end of head unit 62A (Y head next tothe Y head 64 of which data acquisition has been completed as describedabove) face area AR (area indicated by being circled in FIG. 13) of Yscale 39Y₁ on the upper surface of wafer table WTB.

i. Then, main controller 20 performs the processes similar to the aboveto the Y head 64, and stores correction information of Y encoder 70Athat is constituted by the Y head 64 and Y scale 39Y₁ within memory 34.

j. Afterward, in the similar manner, correction information of Y encoder70A that is constituted by each of remaining Y heads 64 of head unit 62Aand Y scale 39Y₁, correction information of X encoder 70B that isconstituted by each of X heads 66 of head unit 62B and X scale 39X₁,correction information of Y encoder 70C that is constituted by each of Yheads 64 of head unit 62C and Y scale 39Y₂, and correction informationof X encoder 70D that is constituted by each of X heads 66 of head unit62D and X scale 39X₂ are respectively obtained and stored in memory 34.

Herein, it is important that similarly to the above-described case, whenperforming the above-described measurement using each X head 66 of headunit 62B, the same area on X scale 39X₁ is used; when performing theabove-described measurement using each Y head 64 of head unit 62C, thesame area on Y scale 39Y₂ is used; and when performing theabove-described measurement using each X head 66 of head unit 62D, thesame area on X scale 39X₂ is used. This is because if correction of eachinterferometer of interferometer system 118 (including correction ofbending of reflection surfaces 17 a and 17 b and reflection surfaces 41a, 41 b and 41 c) has been completed, the attitude of wafer stage WSTcan be set to a desired attitude at any time based on the measurementvalues of those interferometers, and even if the scale surface isinclined, measurement errors do not occur among the heads due to theinclination of the scale surfaces, by using the same portion of eachscale.

Further, regarding Y heads 64 y ₁ and 64 y ₂, main controller 20performs the above-described measurement using the same area on Y scales39Y₂ and 39Y₁ as the area that is used for each Y head 64 of head units62C and 62A respectively, and obtains correction information of Y head64 y ₁ facing Y scale 39Y₂ (encoder 70C) and correction information of Yhead 64 y ₂ facing Y scale 39Y₁ (encoder 70A), and then stores them inmemory 34.

Next, in the similar procedures to the above-described case when thepitching amount is changed, main controller 20 sequentially changes theyawing amount Oz of wafer stage WST in the range of −200 μrad<θz<+200μrad while maintaining both the pitching amount and the rolling amountof wafer stage WST to zero, and drives wafer table WTB (wafer stage WST)in the Z-axis direction in a predetermined range, for example, in arange of −100 μm to +100 μm at each position, and during the driving,sequentially loads the measurement values of the heads at predeterminedsampling intervals and stores them in the internal memory. Suchmeasurement is performed to all heads 64 or heads 66, and each datawithin the internal memory is plotted on a two-dimensional coordinatesystem having the horizontal axis indicating Z-positions and thevertical axis indicating encoder measurement values in the similarprocedures to those described above, plot points at which the yawingamount is the same are sequentially connected, and the horizontal axisis shifted so that a line (a horizontal line in the center) at which theyawing amount is zero passes through the origin, and thereby a graphsimilar to the graph in FIG. 12 is obtained. Then, main controller 20assumes the yawing mount θz, the Z-position, the measurement error ateach point in the obtained graph as table data and stores the table dataas correction information in memory 34. Or, main controller 20 assumesthe measurement error as the mathematical function of a Z-position z andthe yawing amount θz, obtains the mathematical function by computingundetermined coefficients using, for example, the least-squares method,and stores the mathematical function as correction information in memory34.

Herein, in the case the pitching amount of wafer stage is not zero andalso the yawing mount is not zero, it can be considered that themeasurement error of each encoder when wafer stage WST is located at Zposition z is the simple sum (linear sum) of the measurement error inaccordance with the pitching amount described above and the measurementerror in accordance with the yawing amount. This is because it has beenconfirmed as a result of the simulation that the measurement error (acount value (measurement value)) linearly changes in accordance with thechange in the Z-position also in the case where the yawing is changed.

In the following description, for the sake of simplification of theexplanation, it is assumed that regarding the Y heads of each Y encoder,a mathematical function with the pitching amount ex, the yawing amountθz, and the Z-position z of wafer stage WST that shows a measurementerror Δy, as is expressed in the following equation (10), is computedand stored in memory 34. Further, it is assumed that regarding the Xheads of each X encoder, a mathematical function with the rolling amountθy, the yawing amount θz, and the Z-position z of wafer stage WST thatshows a measurement error Δx, as is expressed in the following equation(11), is computed and stored in memory 34.

Δy=f(z,θx,θz)=θx(z−a)+θz(z−b)  (10)

Δx=g(z,θy,θz)=θy(z−c)+θz(z−d)  (11)

In the above equation (10), “a” denotes a Z-coordinate of a point wherethe straight lines intersect in the graph in FIG. 12, and “b” denotes aZ-coordinate of a point where the straight lines intersect in the graphsimilar to the one in FIG. 12 that is obtained in the case the yawingamount is changed in order to acquire correction information of the Yencoders. Further, in the above equation (11), “c” denotes aZ-coordinate of a point where the straight lines intersect in the graphsimilar to the one in FIG. 12 that is obtained in the case the rollingamount is changed in order to acquire correction information of the Xencoders, and “d” denotes a Z-coordinate of a point where the straightlines intersect in the graph similar to the one in FIG. 12 that isobtained in the case the yawing amount is changed in order to acquirecorrection information of the X encoders.

Next, a parallel processing operation using wafer stage WST andmeasurement stage MST in exposure apparatus 100 of the embodiment willbe described based on FIGS. 14 to 27. Incidentally, during the operationdescribed below, main controller 20 performs opening/closing control ofeach valve of liquid supply unit 5 and liquid recovery unit 6 of localliquid immersion unit 8 as is described earlier, and the space on theoutgoing surface side of tip lens 191 of projection optical system PL isconstantly filled with water. However, description regarding control ofliquid supply unit 5 and liquid recovery unit 6 will be omitted in thefollowing description, in order to make the description easilyunderstandable. Further, the following description regarding theoperation will be made using many drawings, but the reference codes ofthe same members are shown in some drawings and not shown in the otherdrawings. That is, the reference codes shown are different in each ofthe drawings, but these drawings show the same configuration regardlessof existence or non-existence of the reference codes. The same is truealso in each of the drawings used in the description above.

FIG. 14 shows a state where exposure by a step-and-scan method is beingperformed to wafer W (in this case, to be a mid wafer of a certain lot(one lot containing 25 or 50 wafers), as an example) on wafer stage WST.At this point in time, measurement stage MST may wait at a withdrawalposition where collision with wafer stage WST is avoided, but in theembodiment, measurement stage MST is moving following wafer stage WSTwhile keeping a predetermined distance between them. Therefore, the samedistance as the predetermined distance is sufficient as a movingdistance of measurement stage MST that is needed when going into thecontact state (or proximity state) with wafer stage WST described aboveafter the exposure ends.

During the exposure, main controller 20 controls the position (includingthe Oz rotation) within the XY plane of wafer table WTB (wafer stageWST), based on the measurement values of at least three encoders out oftwo X heads 66 indicated by being circled in FIG. 14 that face X scales39X₁ and 39X₂ respectively (X encoders 70B and 70D) and two Y heads 64indicated by being circled in FIG. 14 that face Y scales 39Y₁ and 39Y₂respectively (Y encoders 70A and 70C), and based on correctioninformation of each encoder (correction information computed in theequation (10) or (11)) stored in memory 34 in accordance with thepitching amount, the rolling amount, the yawing amount and theZ-position of wafer stage WST that are measured by interferometer system118. Further, main controller 20 controls the position in the Z-axisdirection, and the θy rotation (rolling) and the ex rotation (pitching)of wafer table WTB, based on the measurement values of a pair of Zsensors 74 _(1j) and 74 _(2j), and a pair of Z sensors 76 _(1q) and 76_(2q) that respectively face the end portions on one side and the otherside in the X-axis direction of the wafer table WTB surface (Y scales39Y₁ and 39Y₂ in the embodiment). Incidentally, the position in theZ-axis direction and the θy rotation (rolling) of wafer table WTB may becontrolled based on the measurement values of Z sensors 74 _(1j) and 74_(2j), and 76 _(1q) and 76 _(2q) and the θx rotation (pitching) may becontrolled based on the measurement values of Y interferometer 16. Ineither case, the control of the position in the Z-axis direction, the θyrotation and θx rotation of wafer table WTB (focus leveling control ofwafer W) during the exposure is performed based on the results of thefocus mapping that was performed beforehand by the multipoint AF systemdescribed earlier.

The foregoing exposure operation is performed by main controller 20repeating a moving operation between shots in which wafer stage WST ismoved to a scanning starting position (accelerating starting position)for exposure of each shot area on wafer W based on the result of waferalignment (e.g. Enhanced Global Alignment (EGA)) performed beforehand,the latest baselines of alignment systems AL1 and AL2 ₁ to AL2 ₄, andthe like, and a scanning exposure operation in which a pattern formed onreticle R is transferred to each shot area by a scanning exposuremethod. Incidentally, the exposure operation described above isperformed in a state where water is held in the space between tip lens191 and wafer W. Further, the exposure operation is performed in theorder from the shot area located on the −Y side to the shot area locatedon the +Y side in FIG. 14. Incidentally, the EGA method is disclosed in,for example, the U.S. Pat. No. 4,780,617 and the like.

Then, before the last shot area on wafer W is exposed, main controller20 moves measurement stage MST (measurement table MTB) to the positionshown in FIG. 15 by controlling stage drive system 124 based on themeasurement value of Y interferometer 18 while maintaining themeasurement value of x interferometer 130 to a constant value. At thispoint in time, the end surface on the −Y side of CD bar 46 (measurementtable MTB) and the end surface on the +Y side of wafer table WTB are incontact with each other. Incidentally, the noncontact state (proximitystate) may also be kept by, for example, monitoring the measurementvalues of the interferometer or the encoder that measures the Y-axisdirection position of each table and separating measurement table MTBand wafer table WTB in the Y-axis direction at a distance of around 300μm. Wafer stage WST and measurement stage MST are set in the positionalrelation shown in FIG. 15 during exposure of wafer W, and after that,both the stages are moved so as to keep the positional relation.

Subsequently, as is shown in FIG. 16, while keeping the positionalrelation in the Y-axis direction between wafer table WTB and measurementtable MTB, main controller 20 starts an operation of driving measurementstage MST in the −Y direction and also starts an operation of drivingwafer stage WST toward unloading position UP. When these operations arestarted, in the embodiment, measurement stage MST is moved only in the−Y direction, and wafer stage WST is moved in the −Y direction and −Xdirection.

When main controller 20 drives wafer stage WST and measurement stage MSTsimultaneously as is described above, water that is held in the spacebetween tip lens 191 of projection unit PU and wafer W (water in liquidimmersion area 14 shown in FIG. 16) sequentially moves from wafer W toplate 28, CD bar 46, and measurement table MTB, according to movement ofwafer stage WST and measurement stage MST to the −Y side. Incidentally,during the foregoing movement, the contact state (or proximity state) ofwafer table WTB and measurement table MTB is maintained. Incidentally,FIG. 16 shows a state right before water in liquid immersion area 14 isdelivered from plate 28 to CD bar 46. Further, in the state shown inFIG. 16, main controller 20 controls the position within the XY plane(including the θz rotation) of wafer table WTB (wafer stage WST), basedon the measurement values of three encoders 70A, 70B and 70D (andcorrection information of encoders 70A, 70B or 70D stored in memory 34in accordance with the pitching amount or the rolling amount and theyawing amount, and the Z-position of wafer stage WST that are measuredby interferometer system 118).

When wafer stage WST and measurement stage MST are simultaneously andslightly driven further in the above-described directions respectivelyfrom the state of FIG. 16, position measurement of wafer stage WST(wafer table WTB) by Y encoders 70A (and 70C) cannot be performed.Therefore, right before that, main controller 20 switches the control ofthe Y-position and the θz rotation of wafer stage WST (wafer table WTB)from the control based on the measurement values of Y encoders 70A and70C to the control based on the measurement values of Y interferometer16 and Z interferometers 43A and 43B. Then, after a predetermined periodof time, as is shown in FIG. 17, measurement stage MST reaches aposition where baseline measurement of the secondary alignment systems(hereinafter, also referred to as the Sec-BCHK (interval) as needed)that is performed at predetermined intervals (in this case, with respectto each wafer replacement) is performed. Then, main controller 20 stopsmeasurement stage MST at the position, and also drives further waferstage WST toward unloading position UP while measuring the X-position ofwafer stage WST by X head 66 indicated by being circled in FIG. 17 thatfaces X scale 39X₁ (X-linear encoder 70B) and measuring the Y-position,the θz rotation and the like by Y interferometer 16 and Zinterferometers 43A and 43B, and stops wafer stage WST at unloadingposition UP. Incidentally, in the state of FIG. 17, water is held in thespace between measurement table MTB and tip lens 191.

Subsequently, as is shown in FIGS. 17 and 18, main controller 20 adjuststhe θz rotation of CD bar 46 based on the measurement values of Y-axislinear encoders 70E and 70F described above that are constituted by Yheads 64 y ₁ and 64 y ₂ indicated by being circled in FIG. 18 thatrespectively face a pair of reference gratings 52 on CD bar 46 supportedby measurement stage MST, and also adjusts the XY-position of CD bar 46based on the measurement value of primary alignment system AL1 indicatedby being circled in FIG. 18 that detects reference mark M that islocated on centerline CL of measurement table MTB or in the vicinitythereof. Then, in this state, main controller 20 performs the Sec-BCHK(interval), in which baselines of four secondary alignment systems AL2 ₁to AL2 ₄ (the relative positions of the four secondary alignment systemswith respect to primary alignment system AL1) are severally obtained, bysimultaneously measuring reference marks M on CD bar 46 that are locatedin the field of each secondary alignment system using four secondaryalignment systems AL2 ₁ to AL2 ₄. In parallel with the Sec-BCHK(interval), main controller 20 gives the command and makes a drivesystem of an unload arm (not shown) unload wafer W on wafer stage WSTthat stops at unloading position UP, and also drives wafer stage WST inthe +X direction to move it to loading position LP with a verticalmovement pin CT (not shown in FIG. 17, refer to FIG. 18), which has beendriven upward when performing the unloading, kept upward a predeterminedamount.

Next, as is shown in FIG. 19, main controller 20 moves measurement stageMST to an optimal waiting position (hereinafter, referred to as an“optimal scrum waiting position”) used to shift a state of measurementstage MST from a state of being away from wafer stage WST to the contactstate (or proximity state) with wafer stage WST described previously. Inparallel with this operation, main controller 20 gives the command andmakes a drive system of a load arm (not shown) load new wafer W ontowafer table WTB. In this case, since the state where vertical movementpin CT is raised upward a predetermined amount is maintained, the waferloading can be performed in a shorter period of time, compared with thecase where vertical movement pin CT is driven downward to be housedinside the wafer holder. Incidentally, FIG. 19 shows the state wherewafer W is loaded on wafer table WTB.

In the embodiment, the foregoing optimal scrum waiting position ofmeasurement stage MST is appropriately set in accordance with theY-coordinates of the alignment marks arranged in the alignment shotareas on the wafer. Further, in the embodiment, the optimal scrumwaiting position is set so that the shift to the contact state (orproximity state) described above can be performed at a position wherewafer stage WST stops for the wafer alignment.

Next, as is shown in FIG. 20, main controller 20 moves wafer stage WSTfrom loading position LP to a position with which the position offiducial mark FM on measurement plate 30 is set within the field(detection area) of primary alignment system AL1 (i.e. the positionwhere the former process of baseline measurement of the primaryalignment system (Pri-BCHK) is performed). In the middle of themovement, main controller 20 switches control of the position within theXY plane of wafer table WTB from the control based on the measurementvalue of encoder 70B regarding the X-axis direction described above andthe measurement values of Y interferometer 16 and Z interferometers 43Aand 43B regarding the Y-axis direction and the θz rotation, to thecontrol of the position within the XY plane based on the measurementvalues of at least three encoders, which are at least one of two x heads66 indicated by being circled in FIG. 20 that face X scales 39X₁ and39X₂ (encoders 70B and 70D) and two Y heads 64 y ₂ and 64 y ₁ indicatedby being circled in FIG. 20 that face Y scales 39Y₁ and 39Y₂ (encoders70A and 70C), and based on correction information of each encoder(correction information computed in the above-described equations (10)and (11)) stored in memory 34 in accordance with the pitching amount,the rolling amount and the yawing amount, and the Z-position of waferstage WST that are measured by interferometer system 118.

Then, main controller 20 performs the Pri-BCHK former process in whichfiducial mark FM is detected using primary alignment system AL1. At thispoint in time, measurement stage MST is waiting at the optimal scrumwaiting position described above.

Next, main controller 20 starts movement of wafer stage WST in the +Ydirection toward a position where the alignment marks arranged in thethree first alignment shot areas are detected, while controlling theposition of wafer stage WST based on the measurement values of at leastthree encoders and the correction information described above.

Then, when wafer stage WST reaches the position shown in FIG. 21, maincontroller 20 stops wafer stage WST. Prior to this operation, maincontroller 20 activates (turns ON) Z sensors 72 a to 72 d and measuresthe Z-position and the inclination (the θy rotation and the θx rotation)of wafer table WTB at the point in time when Z sensors 72 a to 72 d facewafer table WTB, or before that point in time.

After the stop of wafer stage WST described above, main controller 20almost simultaneously and individually detects the alignment marksarranged in the three first alignment shot areas (refer to star-shapedmarks in FIG. 21) using primary alignment system AL1 and secondaryalignment systems AL2 ₂ and AL2 ₃, and links the detection results ofthree alignment systems AL1, AL2 ₂ and AL2 ₃ and the measurement valuesof at least three encoders described above at the time of the detection(the measurement values after correction by the correction information),and stores them in an internal memory.

As is described above, in the embodiment, the shift to the contact state(or proximity state) of measurement stage MST and wafer stage WST iscompleted at the position where detection of the alignment marks in thefirst alignment shot areas is performed, and from the position, themovement in the +Y direction (step movement toward a position where thealignment marks arranged in the five second alignment shot areas aredetected) of both stages WST and MST in the contact state (or proximitystate) is started by main controller 20. Prior to the start of movementin the +Y direction of both stages WST and MST, as is shown in FIG. 21,main controller 20 starts irradiation of detection beams fromirradiation system 90 a of the multipoint AF system (90 a, 90 b) towardwafer table WTB. With this operation, the detection area of themultipoint AF system is formed on wafer table WTB.

Then, during the movement of both stages WST and MST in the +Ydirection, when both stages WST and MST reach the position shown in FIG.22, main controller 20 performs the focus calibration former process,and obtains a relation between the measurement values of z sensors 72 a,72 b, 72 c and 72 d (surface position information at the end portions onone side and the other side in the X-axis direction of wafer table WTB)and the detection result (surface position information) at the detectionpoint (the detection point located in the center or in the vicinitythereof, out of a plurality of detection points) on the measurementplate 30 surface by the multipoint AF system (90 a, 90 b) in a statewhere a straight line (centerline) in the Y-axis direction passingthrough the center of wafer table WTB (which substantially coincideswith the center of wafer W) coincides with straight line LV. At thispoint in time, liquid immersion area 14 is located near the boundarybetween CD bar 46 and wafer table WTB. That is, liquid immersion area 14is about to be delivered from CD bar 46 to wafer table WTB.

Then, when both stages WST and MST further move in the +Y directionwhile keeping their contact state (or proximity state) and reach theposition shown in FIG. 23, main controller 20 almost simultaneously andindividually detects the alignment marks arranged in the five secondalignment shot areas (refer to star-shaped marks in FIG. 23) using fivealignment systems AL₁ and AL2 ₁ to AL2 ₄, links the detection results offive alignment systems AL₁ and AL2 ₁ to AL2 ₄ and the measurement valuesof three encoders 70A, 70C and 70D at the time of the detection (themeasurement values after correction by the correction information), andstores them in the internal memory. At this point in time, since thereis no X head that faces X scale 39X₁ and is located on straight line LVin the Y-axis direction that passes through the optical axis ofprojection optical system PL, main controller 20 controls the positionwithin the XY plane of wafer table WTB based on the measurement valuesof X head 66 facing X scale 39X₂ (X linear encoder 70D) and Y linearencoders 70A and 70C.

As is described above, in the embodiment, eight pieces in total ofposition information (two-dimensional position information) of alignmentmarks can be detected at the point in time when detection of thealignment marks in the second alignment shot areas ends. Then, at thisstage, main controller 20 obtains the scaling (shot magnification) ofwafer W by, for example, performing a statistical computation, which isdisclosed in, for example, Kokai (Japanese Unexamined Patent ApplicationPublication) No. 61-044429 (the corresponding U.S. Pat. No. 4,780,617)and the like, using the position information, and based on the computedshot magnification, main controller 20 may also adjust opticalcharacteristics of projection optical system PL, for example, theprojection magnification by controlling an adjustment unit 68 (refer toFIG. 6). Adjustment unit 68 adjusts optical characteristics ofprojection optical system PL by, for example, driving a specific movablelens constituting projection optical system PL or changing the pressureof gas inside the airtight room that is formed between specific lensesconstituting projection optical system PL, or the like.

Further, after the simultaneous detection of the alignment marksarranged in the five second alignment shot areas ends, main controller20 starts again movement in the +Y direction of both stages WST and MSTin the contact state (or proximity state), and at the same time, startsthe focus mapping in which Z sensors 72 a to 72 d and the multipoint AFsystem (90 a, 90 b) are simultaneously used, as is shown in FIG. 23.

Then, when both stages WST and MST reach the position with whichmeasurement plate 30 is located directly below projection optical systemPL shown in FIG. 24, main controller 20 performs the Pri-BCHK latterprocess and the focus calibration latter process. Herein, the Pri-BCHKlatter process means the process in which projected images (aerialimages) of a pair of measurement marks on reticle R that are projectedby projection optical system PL are measured using aerial imagemeasuring unit 45 described above that has aerial image measurement slitpatterns SL formed at measurement plate 30, and the measurement results(aerial image intensity in accordance with the XY-position of wafertable WTB) are stored in the internal memory. In this process, similarlyto the method disclosed in the U.S. Patent Application Publication No.2002/0041377 described earlier and the like, the projected images of apair of measurement marks are measured in the aerial image measurementoperation by a slit-scan method using aerial image measurement slitpatterns SL in pairs. Further, the focus calibration latter processmeans the process in which, as is shown in FIG. 24, while controllingthe position in the optical axis direction of projection optical systemPL (Z-position) of measurement plate 30 (wafer table WTB) based onsurface position information of wafer table WTB (wafer stage WST)measured by Z sensors 72 a, 72 b, 72 c and 72 d, main controller 20measures the aerial images of the measurement marks formed on the markplate (not shown) on reticle R or reticle stage RST, and based on themeasurement results, measures the best focus position of projectionoptical system PL. The measurement operation of projected images of themeasurement marks is disclosed in, for example, the pamphlet ofInternational Publication No. WO 05/124834 and the like. Main controller20 loads the measurement values of Z sensors 74 _(1,4), 74 _(2,4), 76_(1,3) and 76 _(2,3), synchronously with the loading of the outputsignal from aerial image measuring unit 45, while moving measurementplate 30 in the Z-axis direction. Then, main controller 20 stores thevalues of Z sensors 74 _(1,4), 74 _(2,4), 76 _(1,3) and 76 _(2,3) thatcorrespond to the best focus position of projection optical system PL ina memory (not shown). Incidentally, the reason why the position in theoptical axis direction of projection optical system PL (Z-position) ofmeasurement plate 30 (wafer table WTB) is controlled using the surfaceposition information measured by z sensors 72 a, 72 b, 72 c and 72 d inthe focus calibration latter process is that the focus calibrationlatter process is performed in the middle of the focus mapping describedpreviously.

In this case, since liquid immersion area 14 is formed betweenprojection optical system PL and measurement plate 30 (wafer table WTB),the above-described aerial image measurement is performed via projectionoptical system PL and water Lq. Further, because measurement plate 30and the like are mounted at wafer stage WST (wafer table WTB) and thephotodetection element and the like are mounted at measurement stageMST, the above-described aerial image measurement is performed whilekeeping the contact state (or proximity state) of wafer stage WST andmeasurement stage MST, as is shown in FIG. 24. With the measurementdescribed above, the measurement values of Z sensors 74 _(1,4), 74_(2,4), 76 _(1,3) and 76 _(2,3) (i.e. surface position information ofwafer table WTB) in the state where a straight line (centerline) in theY-axis direction passing through the center of wafer table WTB coincideswith straight line LV, which corresponds to the best focus position ofprojection optical system PL, are obtained.

Then, main controller 20 computes the baseline of primary alignmentsystem AL1 based on the result of the Pri-BCHK former process describedearlier and the result of the Pri-BCHK latter process described earlier.Along with this operation, based on a relation between the measurementvalues of Z sensors 72 a, 72 b, 72 c and 72 d (surface positioninformation of wafer table WTB) and the detection result (surfaceposition information) at the detection points on the measurement plate30 surface of the multipoint AF system (90 a, 90 b) that has beenobtained in the focus calibration former process, and based on themeasurement values of Z sensors 74 _(1,4), 74 _(2,4), 76 _(1,3) and 76_(2,3) (i.e. surface position information of wafer table WTB)corresponding to the best focus position of projection optical system PLthat have been obtained in the focus calibration latter process, maincontroller 20 obtains the offset at a representative detection point (inthis case, a detection point located in the center or in the vicinitythereof, out of a plurality of detection points), of the multipoint AFsystem (90 a, 90 b) with respect to the best focus position ofprojection optical system PL, and adjusts the detection origin of themultipoint AF system, for example, in the optical method so that theoffset becomes zero.

In this case, from the viewpoint of improving throughput, only one ofthe Pri-BCHK latter process and the focus calibration latter process maybe performed, or the procedure may shift to the next process withoutperforming both processes. As a matter of course, in the case thePri-BCHK latter process is not performed, the Pri-BCHK former processdoes not need to be performed either. And, in this case, main controller20 only has to move wafer stage WST from loading position LP to aposition at which the alignment marks arranged in the first alignmentshot areas AS are detected. Incidentally, in the case the Pri-BCHKprocess is not performed, the baseline, which was measured in thesimilar operation just before exposure of a wafer that is previous towafer W subject to exposure, is used. Further, in the case the focuscalibration latter process is not performed, the best focus position ofprojection optical system PL that was measured just before exposure of aprevious wafer, similar to the case of the baseline.

Incidentally, in the state of FIG. 24, the focus mapping described aboveis being continued.

When wafer stage WST reaches the position shown in FIG. 25 by movementin the +Y direction of both stages WST and MST in the contact state (orproximity state) described above after a predetermined period of time,main controller 20 stops wafer stage WST at that position, and alsocontinues the movement of measurement stage MST in the +Y directionwithout stopping it. Then, main controller 20 almost simultaneously andindividually detects the alignment marks arranged in the five thirdalignment shot areas (refer to star-shaped marks in FIG. 25) using fivealignment systems AL1 and AL2 ₁ to AL2 ₄, links the detection results offive alignment systems AL1 and AL2 ₁ and AL2 ₄ and the measurementvalues of at least three encoders out of the four encoders at the timeof the detection (the measurement values after correction by thecorrection information) and stores them in the internal memory. At thispoint in time, the focus mapping is being continued.

On the other hand, after a predetermined period of time from the stop ofwafer stage WST described above, the state of measurement stage MST andwafer stage WST shifts from the contact state (or proximity state) tothe separation state. After the shift to the separation state, whenmeasurement stage MST reaches an exposure start waiting position wheremeasurement stage MST waits until exposure is started, main controller20 stops measurement stage MST at the position.

Next, main controller 20 starts movement of wafer stage WST in the +Ydirection toward a position at which the alignment marks arranged inthree fourth alignment shot areas are detected. At this point in time,the focus mapping is being continued. Meanwhile, measurement stage MSTis waiting at the exposure start waiting position described above.

Then, when wafer stage WST reaches the position shown in FIG. 26, maincontroller 20 immediately stops wafer stage WST, and almostsimultaneously and individually detects the alignment marks arranged inthe three fourth alignment shot areas on wafer W (refer to star-shapedmarks in FIG. 26) using primary alignment system AL1 and secondaryalignment systems AL2 ₂ and AL2 ₃, links the detection results of threealignment systems AL1, AL2 ₂ and AL2 ₃ and the measurement values of atleast three encoders out of the four encoders at the time of thedetection (the measurement values after correction by the correctioninformation), and stores them in the internal memory. Also at this pointin time, the focus mapping is being continued, and measurement stage MSTis still waiting at the exposure start waiting position. Then, maincontroller 20 computes array information (coordinate values) of all theshot areas on wafer W in a coordinate system that is set by themeasurement axes of the four encoders (e.g. the XY coordinate systemassuming the center of wafer table WTB as its origin), for example, bythe EGA method disclosed in, for example, the U.S. Pat. No. 4,780,617and the like, using the detection results of 16 alignment marks in totalobtained as is described above and the corresponding measurement valuesof the encoders (measurement values after correction by the correctioninformation).

Next, main controller 20 continues the focus mapping while moving waferstage WST in the +Y direction again. Then, when the detection beam fromthe multipoint AF system (90 a, 90 b) begins to miss the wafer Wsurface, as is shown in FIG. 27, main controller 20 ends the focusmapping. After that, based on the result of the foregoing waferalignment (EGA) performed beforehand, the latest baselines of fivealignment systems AL1 and AL2 ₁ to AL2 ₄, and the like, main controller20 performs exposure by a step-and-scan method in a liquid immersionexposure method and sequentially transfers a reticle pattern on aplurality of shot areas on wafer W. Afterwards, the similar operationsare repeatedly performed in order to expose the remaining wafers withinthe lot.

Incidentally, in order to simplify the explanation in the foregoingdescription, main controller 20 is to perform the control of therespective constituents of the exposure apparatus such as the stagesystem, but the present invention is not limited to thereto, and it goeswithout saying that at least part of the above-described controlperformed by main controller 20 may be shared and performed by aplurality of controllers. For example, a stage controller that performsthe control of wafer stage WST and the like based on the measurementvalues of the encoder system, the Z sensors and the interferometersystem may be arranged under the control of main controller 20. Further,the above-described control performed by main controller 20 does notalways have to be realized by hardware, but it may be realized insoftware-wise by a computer program that sets an operation of maincontroller 20 or each of several controllers that share and perform thecontrol as is described above.

As is described above in detail, according to exposure apparatus 100 ofthe embodiment, in the case wafer stage WST is moved in a predetermineddirection, for example, in the Y-axis direction when wafer alignment,exposure or the like is performed, wafer stage WST is driven in theY-axis direction based on measurement information of the encoder systemand position information (including inclination information, and forexample, rotation information in the ex direction) of wafer stage WST ina direction different from the Y-axis direction. That is, wafer stageWST is driven so that measurement errors of the encoder system (encoders70A and 70C), which occur due to the displacement (includinginclination) of wafer stage WST in a different direction from the Y-axisdirection, are compensated. In the embodiment, main controller 20 driveswafer stage WST in the Y-axis direction, based on the measurement valuesof encoders 70A and 70C that measure position information of wafer stageWST in the Y-axis direction, and based on correction information(correction information computed in the equation (10) described above)in accordance with position information in a direction (non-measurementdirection) different from the Y-axis direction of wafer stage WST at thetime of the measurement, for example, in accordance with positioninformation of wafer stage WST in the ex direction, the θz direction andthe Z-axis direction that are measured by Y interferometer 16 and Zinterferometers 43A and 43B of interferometer system 118. In thismanner, based on the measurement values of encoders 70A and 70C, whosemeasurement errors caused by the relative displacement of head 64 andscale 39Y₁ or 39Y₂ in the non-measurement direction have been correctedby the correction information, stage drive system 124 is controlled andwafer stage WST is driven in the Y-axis direction.

Further, in the case wafer stage WST is moved in the X-axis direction,wafer wage WST is driven in the X-axis direction based on measurementinformation of the encoder system and position information of waferstage WST in a different direction from the X-axis direction (includinginclination information, and for example, rotation information in the θydirection). That is, wafer stage WST is driven so that measurementerrors of the encoder system (encoders 70B and 70D), which occur due toby the displacement (including inclination) of wafer stage WST in adifferent direction from the X-axis direction, are compensated. In theembodiment, main controller 20 drives wafer stage WST in the X-axisdirection, based on the measurement values of encoders 70B and 70D thatmeasure position information of wafer stage WST in the X-axis direction,and based on correction information (correction information computed inthe equation (11) described above) in accordance with positioninformation of wafer stage WST in a direction (non-measurementdirection) different from the X-axis direction at the time of themeasurement, for example, in accordance with position information ofwafer stage WST in the θy direction, the θz direction and the Z-axisdirection that are measured by Z interferometers 43A and 43B ofinterferometer system 118. Accordingly, wafer stage WST can accuratelybe driven in a desired direction without being affected by the relativemotion between the heads and the scales in directions other than adirection that should be measured (measurement direction).

Further, according to exposure apparatus 100 of the embodiment, for therelative movement of wafer W and illumination light IL, which isirradiated from illumination system 10 to wafer W via reticle R,projection optical system PL and water Lq, main controller 20 accuratelydrives wafer stage WST that mounts wafer W, based on the measurementvalues of the encoders described above and position information of thewafer stage in the non-measurement direction at the time of themeasurement. Accordingly, a pattern of reticle R can be formed on thewafer with high accuracy by scanning exposure and liquid immersionexposure.

Further, according to the embodiment, when acquiring correctioninformation of the measurement value of the encoder, main controller 20changes the attitude of wafer stage WST to a plurality of differentattitudes, and moves wafer stage WST in the Z-axis direction in apredetermined stroke range while irradiating a detection light from head64 or 66 of the encoder to a specific area of scale 39Y₁, 39Y₂, 39X₁ or39X₂ in a state where the attitude of wafer stage WST is maintainedbased on the measurement results of interferometer system 118 withrespect to each attitude, and performs the sampling of the measurementresults of the encoder during the movement. With this operation, withrespect to each attitude, variation information of the measurementvalues of the encoder in accordance with the position in a direction(the Z-axis direction) orthogonal to the moving plane of wafer stage WST(e.g. the characteristic curve as shown in the graph of FIG. 12) isobtained.

Then, main controller 20 obtains correction information of themeasurement value of the encoder in accordance with position informationof wafer stage WST in the non-measurement direction, by performing apredetermined computation based on the sampling results, that is, thevariation information of the measurement values of the encoder inaccordance with the position of wafer stage WST in the Z-axis directionwith respect to each attitude. Accordingly, correction information forcorrecting the measurement error of the encoder caused by the relativechange of the head and the scale in the non-measurement direction can bedecided in the simple method.

Further, in the embodiment, in the case the correction information isdecided with respect to a plurality of heads that constitute the samehead unit, for example, a plurality of Y heads 64 that constitute headunit 62A, a detection light is irradiated from each Y head 64 to thesame specific area of corresponding Y scale 39Y₁ and performs theabove-described sampling of measurement results of the encoder, and thenbased on the sampling results, the correction information of eachencoder that is constituted by each Y head 64 and Y scale 39Y₁ isdecided. Therefore, as a consequence, a geometric error that occurs dueto gradient of the head is also corrected. In other words, whenobtaining the correction information for a plurality of encoders thatcorrespond to the same scale, main controller 20 obtains correctioninformation of a subject encoder, taking into consideration a geometricerror that occurs due to gradient of the head of the subject encoderwhen wafer stage WST is moved in the Z-axis direction. Accordingly, inthe embodiment, a cosine error that is caused by different gradientangles of a plurality of heads does not occur. Further, in the case ameasurement error occurs in the encoder due to, for example, opticalcharacteristics of the head (such as telecentricity) even if gradient ofY head 64 does not occur, occurrence of the measurement error,occurrence of the measurement error can be prevented, and thereforereduction in position control accuracy of wafer stage WST can beprevented, by similarly obtaining the correction information. That is,in the embodiment, wafer stage WST is driven so that the measurementerror of the encoder system occurring due to the head unit (hereinafter,also referred to as the head-attributable error) is compensated.Incidentally, based on characteristics information of the head unit(e.g. including gradient of the head, and/or optical characteristics),for example, correction information of the measurement values of theencoder system may be computed.

Incidentally, the configuration and the placement of the encoder system,the interferometer system, the multipoint AF system and the Z sensors inthe embodiment are merely examples, and it goes without saying that thepresent invention is not limited to them. For example, in the embodimentabove, the case has been exemplified where a pair of Y scales 39Y₁ and39Y₂ used for the Y-axis direction position measurement and a pair of Xscales 39X₁ and 39X₂ used for the X-axis direction position measurementare arranged on wafer table WTB, and so as to correspond to them, a pairof head units 62A and 62C are placed on one side and the other side ofthe X-axis direction of projection optical system PL and a pair of headunits 62B and 62D are placed on one side and the other side of theY-axis direction of projection optical system PL. However, the presentinvention is not limited to this, and only one scale of at least eitherpair of Y scales 39Y₁ and 39Y₂ for Y-axis direction position measurementor X scales 39X₁ and 39X₂ for X-axis direction position measurement maybe arranged alone, not in pairs on wafer table WTB, or only one headunit of at least either pair of head units 62A and 62C or head units 62Band 62D may be arranged. Further, the direction in which the scales arearranged and the direction in which the head units are arranged are notlimited to orthogonal directions such as the X-axis direction and theY-axis direction as in the embodiment above, but only have to bedirections that intersect each other. Further, the periodic direction ofthe diffraction grating may be a direction orthogonal to (orintersecting) a longitudinal direction of each scale, and in this case,a plurality of heads of the corresponding head unit only have to bearranged in the direction orthogonal to the periodic direction ofdiffraction grating. Further, each head unit may have a plurality ofheads that are densely arranged in a direction orthogonal to theperiodic direction of the diffraction grating.

Further, in the embodiment above, the case has been exemplified wherethe encoder system is employed that has the configuration in which agrating section (the X scales and the Y scales) are arranged on thewafer table (wafer stage), and so as to face the scale section, the headunits (the X heads and the Y heads) are placed outside the wafer stage.However, the present invention is not limited to such an encoder system,and an encoder system having the configuration in which encoder headsare arranged on a wafer stage and so as to face the encoder heads,two-dimensional gratings (or two-dimensionally placed one-dimensionalgrating sections) are placed outside the wafer stage may also beemployed. In this case, when Z sensors are also placed on the uppersurface of the wafer stage, the two-dimensional gratings (ortwo-dimensionally placed one-dimensional grating sections) may also beused as the reflection surfaces that reflect the measurement beams fromthe Z sensors. Also in the case the encoder system having such aconfiguration is employed, basically in the similar procedures to thosein the embodiment above, wafer stage WST can be driven based on themeasurement values of the encoders whose measurement errors due to therelative displacement of the heads and the scales in the non-measurementdirection are corrected by correction information. With this operation,wafer stage WST can be driven in a desired direction with high accuracy,without being affected by the relative motion between the head and thescale in directions other than the direction to be measured (measurementdirection). Further, in the simple method similar to the one in theembodiment above, correction information for correcting measurementerrors of the encoders caused by the relative change of the heads andthe scales in the non-measurement direction can be decided.

Incidentally, in the embodiment above, rotation information in the θxdirection (the pitching amount) of wafer stage WST is to be measured byinterferometer system 118, but the pitching amount may also be obtainedfrom, for example, the measurement values of a pair of Z sensors 74_(ij) or Z sensors 76 _(pq). Or, for example, one or a pair of Zsensor(s) is/are arranged adjacent to each head of heads units 62B and62D, similarly to head units 62A and 62C, and the pitching amount mayalso be obtained from the measurement values of the Z sensors that faceX scales 39 ₁ and 39X₂ respectively. With this operation, positioninformation of wafer stage WST in directions of six degrees of freedom,that is, the X-axis, Y-axis, Z-axis, θx, θy and θz directions can bemeasured using the encoders and the Z sensors, without usinginterferometer system 118. The above-described measurement of positioninformation of wafer stage WST in directions of six degrees of freedomby the encoders and the Z sensors may be performed not only in theexposure operation, but also in the alignment operation and/or the focusmapping operation described earlier.

Further, in the embodiment above, the measurement values of the encodersystem are to be corrected based on the correction information describedearlier so that the measurement error of the encoder system, whichoccurs due to the displacement of wafer stage WST (relative displacementof the head and the scale) in a direction different from a predetermineddirection in which wafer stage WST is driven, is compensated. However,the present invention is not limited thereto, and for example, a targetposition at which the position of wafer stage WST is set may becorrected based on the correction information described above, whiledriving wafer stage WST based on the measurement values of the encodersystem. Or, in the exposure operation in particular, while driving wafersage WST based on, for example, the measurement values of the encodersystem, the position of reticle stage RST may be corrected based on thecorrection information described above.

Further, in the embodiment above, only wafer stage WST is to be drivenbased on the measurement values of the encoder system, for example, whenexposure is performed, but for example, an encoder system that measuresthe position of reticle stage RST is additionally arranged and reticlestage RST may also be driven based on the measurement values of thisencoder system and based on correction information according to positioninformation of the reticle stage in the non-measurement direction thatis measured by reticle interferometer 116.

Further, in the embodiment above, the case has been explained where onefixed primary alignment system and four movable secondary alignmentsystems are equipped, and alignment marks arranged in 16 alignment shotareas on the wafer are detected in the sequence that is proper for thefive alignment systems. However, the secondary alignment systems do nothave to be movable, and the number of secondary alignment systems may beany number. The point is that at least one alignment system that candetect alignment marks on a wafer only has to be arranged.

Incidentally, in the embodiment above, the exposure apparatus equippedwith measurement stage MST separately from wafer stage WST, which issimilar to the exposure apparatus that is disclosed in, for example, thepamphlet of International Publication No. WO 2005/074014 and the like,is described. The present invention is not limited to this type ofexposure apparatus, but as is disclosed in, for example, Kokai (JapaneseUnexamined Patent Application Publication) No. 10-214783 and thecorresponding U.S. Pat. No. 6,341,007, and the pamphlet of InternationalPublication No. WO 98/40791 and the corresponding U.S. Pat. No.6,262,796, and the like, also in a twin-stage type exposure apparatus inwhich an exposure operation and a measurement operation (e.g. markdetection by an alignment system) can be executed substantially inparallel using two wafer stages, position control of each wafer stagecan be performed using the encoder system described above (FIG. 3). Inthis case, by appropriately setting the placement and the length of eachhead unit, position control of each wafer stage can be performed usingthe encoder system described above without any change, not only when theexposure operation is performed but also when the measurement operationis performed. But, another head unit that can be used during themeasurement operation may also be arranged separately from the headunits described above (62A to 62D). For example, four head units thatare placed in the cross arrangement assuming one or two alignmentsystem(s) as its center are arranged, and position information of eachwafer stage WST may also be measured using these head units andcorresponding moving scales (62A to 62D) when the measurement operationis performed. In the twin-stage type exposure apparatus, at least twomoving scales are arranged on each of two wafer stages, and when anexposure operation of a wafer mounted on one stage is finished, theother stage on which a next wafer whose mark detection and the like havebeen performed at a measurement position is to be mounted is placed atan exposure position, in order to replace the one stage. Further, themeasurement operation performed in parallel with the exposure operationis not limited to mark detection of a wafer and the like by an alignmentsystem, but detection of surface information (level differenceinformation) of the wafer may also be performed instead of the markdetection or in combination with the mark detection.

Incidentally, in the embodiment above, the case has been explained wherewhile each wafer replacement is being performed on the wafer stage WSTside, the Sec-BCHK (interval) is performed using CD bar 46 on themeasurement stage MST side. However, the present invention is notlimited to this, and at least one of irregular illuminance measurement(and illuminance measurement), aerial image measurement, wavefrontaberration measurement and the like may be performed using the measuringinstruments (measurement members) of measurement stage MST, and themeasurement result may also be reflected in exposure of a wafer to beperformed after that. Specifically, for example, adjustment ofprojection optical system PL can be performed by adjustment unit 68based on the measurement result.

Further, in the embodiment above, the scales are arranged also onmeasurement stage MST and position control of the measurement stage mayalso be performed using the encoder system (head units) described above.That is, a movable body whose position information is measured by theencoder system is not limited to the wafer stage.

Incidentally, in view of decrease in size and weight of wafer stage WST,the scales are preferably placed as close as possible to wafer W onwafer stage WST. When it is allowed that the size of the wafer stage isincreased, however, two each in the X-axis direction and the Y-axisdirection, that is, a total of four pieces of position information maybe constantly measurable at least in an exposure operation of a wafer byincreasing the size of the wafer stage and increasing the distancebetween a pair of scales placed facing each other. Further, instead ofincreasing the size of the wafer stage, for example, by arranging thescale so that a portion of the scale protrudes from the wafer stage, orplacing a scale on the outer side of the wafer stage main section usingan auxiliary plate on which at least one scale is arranged, the distancebetween a pair of scales arranged facing each other may also beincreased similarly.

Further, in the embodiment above, in order to prevent reduction inmeasurement accuracy due to adherence of foreign particles or stains toY scales 39Y₁ and 39Y₂ and X scales 39X₁ and 39X₂, for example, coatingmay be applied to the surface so as to cover at least the diffractiongratings, or a cover glass may be arranged. In this case, in a liquidimmersion exposure apparatus in particular, a liquid repellentprotective film may also be coated on the scales (grating surfaces), ora liquid repellent film may also be formed on the surface (uppersurface) of the cover glass. Moreover, each scale is to have diffractiongratings that are consecutively formed on the substantially entire areain its longitudinal direction, but for example, diffraction gratings mayalso be intermittently formed on a plurality of divided areas, or eachmoving scale may be constituted by a plurality of scales. Further, inthe embodiment above, the case has been exemplified where an encoder bya diffraction interference method is used as the encoder. However, thepresent invention is not limited to such an encoder, and an encoder by aso-called pickup method, or a magnetic method may also be used, and inaddition, a so-called scan encoder that is disclosed in, for example,the U.S. Pat. No. 6,639,686 and the like may also be used.

Further, in the embodiment above, as the Z sensors, instead of thesensor by the optical pickup method described earlier, for example, asensor having the following configuration may also be used, that is, theconfiguration which is equipped with: a first sensor (which may be asensor by an optical pickup method or other optical displacementsensors) that optically reads the displacement of a measurement-subjectsurface in the Z-axis direction by projecting a probe beam to themeasurement-subject surface and receiving the reflected light; a drivesection that drives the first sensor in the Z-axis direction; and asecond sensor (such as an encoder) that measures the displacement of thefirst sensor in the Z-axis direction. In the Z sensor having suchconfiguration, the following modes can be set, that is, a mode (a firstservocontrol mode) in which the drive section drives the first sensor inthe Z-axis direction based on the output of the first sensor so that adistance in the Z-axis direction between the measurement-subjectsurface, for example, the surface of the scale and the first sensor isconstant at all times, and a mode (a second servocontrol mode) in whichthe target value of the second sensor is given from the outside (thecontroller) and the drive section maintains the position of the firstsensor in the Z-axis direction so that the measurement value of thesecond sensor coincides with the target value. In the case of the firstservocontrol mode, the output of the measurement section (second sensor)can be used as the output of the Z sensor, and in the case of the secondservocontrol mode, the output of the first sensor can be used as theoutput of the Z sensor. Further, in the case such a Z sensor is used andan encoder is employed as the second sensor, as a consequence, positioninformation of wafer stage WST (wafer table WTB) in directions of sixdegrees of freedom can be measured using the encoder. Further, in theembodiment above, as the Z sensor, sensors by other detection methodscan also be employed.

Further, in the embodiment above, the configuration and the combinationof a plurality of interferometers that measure position information ofwafer stage WST are not limited to the configuration and the combinationdescribed above. Any configuration and any combination of theinterferometers may be employed as far as position information of waferstage WST in directions other than the measurement direction of theencoder system can be measured. The point is that a measurement unit(regardless of whether it is an interferometer), which can measureposition information of wafer stage WST in directions other than themeasurement direction of the encoder system, only has to be equipped inaddition to the encoder system described above. For example, theabove-described Z sensors may also be used as the measurement unit.

Further, in the embodiment above, the Z sensors are to be arrangedbesides the multipoint AF system. However, for example, if themultipoint AF system can detect surface position information atexposure-subject shot areas of wafer W when exposure is performed, the Zsensors do not always have to be arranged.

Incidentally, in the embodiment above, pure water (water) is to be usedas liquid, however, the present invention is not limited to this asmatter of course. As the liquid, liquid that is chemically stable,having high transmittance to illumination light IL and safe to use, suchas a fluorine-containing inert liquid may be used. As thefluorine-containing inert liquid, for example, Fluorinert (the brandname of 3M United States) can be used. The fluorine-containing inertliquid is also excellent from the point of cooling effect. Further, asthe liquid, liquid which has a refractive index higher than pure water(a refractive index is around 1.44), for example, liquid having arefractive index equal to or higher than 1.5 may be used. As this typeof liquid, for example, a predetermined liquid having C—H binding or O—Hbinding such as isopropanol having a refractive index of about 1.50,glycerol (glycerin) having a refractive index of about 1.61, apredetermined liquid (organic solvent) such as hexane, heptane ordecane, or decalin (decahydronaphthalene) having a refractive index ofabout 1.60, or the like can be cited. Alternatively, a liquid obtainedby mixing arbitrary two or more of the above-described predeterminedliquids may be used, or a liquid obtained by adding (mixing) thepredetermined liquid to (with) pure water may also be used.Alternatively, as the liquid, a liquid obtained by adding (mixing) baseor acid such as H⁺, Cs⁺, K⁺, Cl⁻, SO₄ ²⁻, or PO₄ ²⁻ to (with) pure watermay also be used. Moreover, a liquid obtained by adding (mixing)particles of Al oxide or the like to (with) pure water may also be used.These liquids can transmit ArF excimer laser light. Further, as theliquid, liquid, which has a small absorption coefficient of light, isless temperature-dependent, and is stable to a projection optical system(tip optical member) and/or a photosensitive agent (or a protective film(topcoat film), an antireflection film, or the like) coated on thesurface of a wafer, is preferable. Further, in the case an F₂ laser isused as the light source, fomblin oil may be selected.

Further, in the embodiment above, the recovered liquid may be reused,and in this case, a filter that removes impurities from the recoveredliquid is preferably arranged in a liquid recovery unit, a recovery pipeor the like.

Incidentally, in the embodiment above, the case has been described wherethe exposure apparatus is a liquid immersion type exposure apparatus.However, the present invention is not limited to thereto, but can alsobe suitably applied to a dry type exposure apparatus that performsexposure of wafer W without liquid (water).

Further, in the embodiment above, the case has been described where thepresent invention is applied to a scanning exposure apparatus by astep-and-scan method or the like. However, the present invention is notlimited to this, but may also be applied to a static exposure apparatussuch as a stepper. Even with the stepper or the like, by measuring theposition of a stage on which an object subject to exposure is mountedusing encoders, occurrence of position measurement error caused by airfluctuations can substantially be nulled likewise. In this case, itbecomes possible to set the position of the stage with high precisionbased on the measurement values of the encoders and the correctioninformation described above, and as a consequence, highly accuratetransfer of a reticle pattern onto the object can be performed. Further,the present invention can also be applied to a reduction projectionexposure apparatus by a step-and-stitch method that synthesizes a shotarea and a shot area, an exposure apparatus by a proximity method, amirror projection aligner, or the like.

Further, the magnification of the projection optical system in theexposure apparatus of the embodiment above is not only a reductionsystem, but also may be either an equal magnifying system or amagnifying system, and projection optical system PL is not only adioptric system, but also may be either a catoptric system or acatadioptric system, and in addition, the projected image may be eitheran inverted image or an upright image. Moreover, the exposure area towhich illumination light IL is irradiated via projection optical systemPL is an on-axis area that includes optical axis AX within the field ofprojection optical system PL. However, for example, as is disclosed inthe pamphlet of International Publication No. WO 2004/107011, theexposure area may also be an off-axis area that does not include opticalaxis AX, similar to a so-called inline type catadioptric system, in partof which an optical system (catoptric system or catadioptric system)that has plural reflection surfaces and forms an intermediate image atleast once is arranged, and which has a single optical axis. Further,the illumination area and exposure area described above are to have arectangular shape. However, the shape is not limited to rectangular, butmay also be circular arc, trapezoidal, parallelogram or the like.

Incidentally, a light source of the exposure apparatus in the embodimentabove is not limited to the ArF excimer laser, but a pulse laser lightsource such as a KrF excimer laser (output wavelength: 248 nm), an F₂laser (output wavelength: 157 nm), an Ar₂ laser (output wavelength: 126nm) or a Kr₂ laser (output wavelength: 146 nm), or an extra-highpressure mercury lamp that generates an emission line such as a g-line(wavelength: 436 nm) or an i-line (wavelength: 365 nm) can also be used.Further, a harmonic wave generating unit of a YAG laser or the like canalso be used. Besides, as is disclosed in, for example, the pamphlet ofInternational Publication No. WO 1999/46835 (the corresponding U.S. Pat.No. 7,023,610), a harmonic wave, which is obtained by amplifying asingle-wavelength laser beam in the infrared or visible range emitted bya DFB semiconductor laser or fiber laser as vacuum ultraviolet light,with a fiber amplifier doped with, for example, erbium (or both erbiumand ytteribium), and by converting the wavelength into ultraviolet lightusing a nonlinear optical crystal, may also be used.

Further, in the embodiment above, illumination light IL of the exposureapparatus is not limited to the light having a wavelength equal to ormore than 100 nm, and it is needless to say that the light having awavelength less than 100 nm may be used. For example, in recent years,in order to expose a pattern equal to or less than 70 nm, an EUVexposure apparatus that makes an SOR or a plasma laser as a light sourcegenerate an EUV (Extreme Ultraviolet) light in a soft X-ray range (e.g.a wavelength range from 5 to 15 nm), and uses a total reflectionreduction optical system designed under the exposure wavelength (e.g.13.5 nm) and the reflective mask has been developed. In the EUV exposureapparatus, the arrangement in which scanning exposure is performed bysynchronously scanning a mask and a wafer using a circular arcillumination can be considered, and therefore, the present invention canalso be suitably applied to such an exposure apparatus. Besides, thepresent invention can also be applied to an exposure apparatus that usescharged particle beams such as an electron beam or an ion beam.

Further, in the embodiment above, a transmissive type mask (reticle),which is a transmissive substrate on which a predetermined lightshielding pattern (or a phase pattern or a light attenuation pattern) isformed, is used. Instead of this reticle, however, as is disclosed in,for example, U.S. Pat. No. 6,778,257, an electron mask (which is alsocalled a variable shaped mask, an active mask or an image generator, andincludes, for example, a DMD (Digital Micromirror Device) that is a typeof a non-emission type image display device (spatial light modulator) orthe like) on which a light-transmitting pattern, a reflection pattern,or an emission pattern is formed according to electronic data of thepattern that is to be exposed may also be used. In the case such avariable shaped mask is used, a stage on which a wafer, a glass plate orthe like is mounted is scanned with respect to the variable shaped mask,and therefore, by measuring the position of the stage using the encoderand by driving the stage based on the measurement values of the encoderand correction information according to position information of thestage in the non-measurement direction that is measured by theinterferometer, the effect equivalent to that of the embodiment abovecan be obtained.

Further, as is disclosed in, for example, the pamphlet of InternationalPublication No. WO 2001/035168, the present invention can also beapplied to an exposure apparatus (lithography system) that formsline-and-space patterns on a wafer by forming interference fringes onthe wafer.

Moreover, the present invention can also be applied to an exposureapparatus that synthesizes two reticle patterns on a wafer via aprojection optical system and almost simultaneously performs doubleexposure of one shot area on the wafer by one scanning exposure, as isdisclosed in, for example, Kohyo (published Japanese translation ofInternational Publication for Patent Application) No. 2004-519850 (thecorresponding U.S. Pat. No. 6,611,316).

Further, an apparatus that forms a pattern on an object is not limitedto the exposure apparatus (lithography system) described above, and forexample, the present invention can also be applied to an apparatus thatforms a pattern on an object by an ink-jet method.

Incidentally, an object on which a pattern is to be formed (an objectsubject to exposure to which an energy beam is irradiated) in theabove-described embodiment and modified example is not limited to awafer, but may be other objects such as a glass plate, a ceramicsubstrate, a film member, or a mask blank.

The usage of the exposure apparatus is not limited to the exposureapparatus used for manufacturing semiconductor devices. The presentinvention can be widely applied also to, for example, an exposureapparatus for manufacturing liquid crystal display devices whichtransfers a liquid crystal display device pattern onto a square-shapedglass plate, and to an exposure apparatus for manufacturing organic EL,thin-film magnetic heads, imaging devices (such as CCDs), micromachines,DNA chips or the like. Further, the present invention can also beapplied to an exposure apparatus that transfers a circuit pattern onto aglass substrate or a silicon wafer not only when producing microdevicessuch as semiconductor devices, but also when producing a reticle or amask used in an exposure apparatus such as an optical exposureapparatus, an EUV exposure apparatus, an X-ray exposure apparatus, andan electron beam exposure apparatus.

Incidentally, the movable body drive system, the movable body drivemethod, or the decision-making method of the present invention can beapplied not only to the exposure apparatus, but can also be appliedwidely to other substrate processing apparatuses (such as a laser repairapparatus, a substrate inspection apparatus and the like), or toapparatuses equipped with a movable body such as a stage that moveswithin a two-dimensional plane such as a position setting apparatus forspecimen or a wire bonding apparatus in other precision machines.

Further, the exposure apparatus (the pattern formation apparatus) of theembodiment above is manufactured by assembling various subsystems, whichinclude the respective constituents that are recited in the claims ofthe present application, so as to keep predetermined mechanicalaccuracy, electrical accuracy and optical accuracy. In order to securethese various kinds of accuracy, before and after the assembly,adjustment to achieve the optical accuracy for various optical systems,adjustment to achieve the mechanical accuracy for various mechanicalsystems, and adjustment to achieve the electrical accuracy for variouselectric systems are performed. A process of assembling varioussubsystems into the exposure apparatus includes mechanical connection,wiring connection of electric circuits, piping connection of pressurecircuits, and the like among various types of subsystems. Needless tosay, an assembly process of individual subsystem is performed before theprocess of assembling the various subsystems into the exposureapparatus. When the process of assembling the various subsystems intothe exposure apparatus is completed, a total adjustment is performed andvarious kinds of accuracy as the entire exposure apparatus are secured.Incidentally, the making of the exposure apparatus is preferablyperformed in a clean room where the temperature, the degree ofcleanliness and the like are controlled.

Incidentally, the above disclosures of the various publications, thepamphlets of the International Publications, and the U.S. PatentApplication Publications and the U.S. patents that are cited in theembodiment above and related to exposure apparatuses and the like areeach incorporated herein by reference.

Next, an embodiment of a device manufacturing method in which theforegoing exposure apparatus (pattern formation apparatus) is used in alithography process will be described.

FIG. 28 shows a flowchart of an example when manufacturing a device (asemiconductor chip such as an IC or an LSI, a liquid crystal panel, aCCD, a thin film magnetic head, a micromachine, and the like). As isshown in FIG. 28, first of all, in step 201 (design step), function andperformance design of device (such as circuit design of semiconductordevice) is performed, and pattern design to realize the function isperformed. Then, in step 202 (mask manufacturing step), a mask on whichthe designed circuit pattern is formed is manufactured. Meanwhile, instep 203 (wafer manufacturing step), a wafer is manufactured usingmaterials such as silicon.

Next, in step 204 (wafer processing step), the actual circuit and thelike are formed on the wafer by lithography or the like in a manner thatwill be described later, using the mask and the wafer prepared in steps201 to 203. Then, in step 205 (device assembly step), device assembly isperformed using the wafer processed in step 204. Step 205 includesprocesses such as the dicing process, the bonding process, and thepackaging process (chip encapsulation), and the like when necessary.

Finally, in step 206 (inspection step), tests on operation, durability,and the like are performed on the devices made in step 205. After thesesteps, the devices are completed and shipped out.

FIG. 29 is a flowchart showing a detailed example of step 204 describedabove. Referring to FIG. 29, in step 211 (oxidation step), the surfaceof wafer is oxidized. In step 212 (CDV step), an insulating film isformed on the wafer surface. In step 213 (electrode formation step), anelectrode is formed on the wafer by deposition. In step 214 (ionimplantation step), ions are implanted into the wafer. Each of the abovesteps 211 to 214 constitutes the pre-process in each stage of waferprocessing, and the necessary processing is chosen and is executed ateach stage.

When the above-described pre-process ends in each stage of waferprocess, post-process is executed as follows. In the post-process, firstin step 215 (resist formation step), a photosensitive agent is coated onthe wafer. Then, in step 216 (exposure step), the circuit pattern of themask is transferred onto the wafer by the exposure apparatus (patternformation apparatus) described above and the exposure method (patternformation method) thereof. Next, in step 217 (development step), thewafer that has been exposed is developed, and in step 218 (etchingstep), an exposed member of an area other than the area where resistremains is removed by etching. Then, in step 219 (resist removing step),when etching is completed, the resist that is no longer necessary isremoved.

By repeatedly performing the pre-process and the post-process, multiplecircuit patterns are formed on the wafer.

By using the device manufacturing method of the embodiment describedabove, because the exposure apparatus (pattern formation apparatus) inthe embodiment above and the exposure method (pattern formation method)thereof are used in the exposure step (step 216), exposure with highthroughput can be performed while maintaining the high overlay accuracy.Accordingly, the productivity of highly integrated microdevices on whichfine patterns are formed can be improved.

While the above-described embodiment of the present invention is thepresently preferred embodiment thereof, those skilled in the art oflithography systems will readily recognize that numerous additions,modifications, and substitutions may be made to the above-describedembodiment without departing from the spirit and scope thereof. It isintended that all such modifications, additions, and substitutions fallwithin the scope of the present invention, which is best defined by theclaims appended below.

What is claimed is:
 1. An exposure apparatus that exposes a substratewith an illumination light via a projection optical system, theapparatus comprising: a frame member that supports the projectionoptical system; a first stage system that has a first stage and a firstdrive system, and moves the first stage at least in a first directionwithin a predetermined plane orthogonal to an optical axis of theprojection optical system, the first stage being disposed above theprojection optical system and holding a mask illuminated with theillumination light, and the first drive system including a first motorto drive the first stage; a second stage system that has a second stageand a second drive system, and moves the second stage at least in thefirst direction and a second direction orthogonal to each other withinthe predetermined plane, the second stage being disposed below theprojection optical system and holding the substrate, and the seconddrive system including a second motor to drive the second stage; a firstmeasurement system and a second measurement system that measurepositional information of the first stage and positional information ofthe second stage, respectively, the second measurement system having anencoder system in which one of a grating section and heads is providedat the second stage and the other of the grating section and the headsis provided at the frame member so that the other of the grating sectionand the heads faces the second stage, and which measures the positionalinformation of the second stage with a plurality of the heads that facethe grating section, and the grating section having a reflective gratingthat is periodic in a direction parallel to the predetermined plane; anda controller coupled to the first and the second stage systems and thefirst and the second measurement systems, wherein the controllercontrols the first and the second drive systems based on measurementinformation of the first and the second measurement systems andcorrection information for compensating for a measurement error of theencoder system related to a measurement direction of the positionalinformation by the heads so that, in an exposure operation of thesubstrate, scanning exposure in which the mask and the substrate areeach moved relative to the illumination light is performed with thefirst direction serving as a scanning direction and also the measurementerror is compensated, the measurement error occurring due to a relativemotion between the heads and the grating section in a differentdirection that is different from the measurement direction.
 2. Theexposure apparatus according to claim 1, wherein the other of thegrating section and heads is supported in a suspended manner by theframe member via a support member.
 3. The exposure apparatus accordingto claim 1, wherein the second stage is provided with the heads, and ismoved below the grating section.
 4. The exposure apparatus according toclaim 1, wherein the measurement direction includes a direction parallelto the predetermined plane, and the different direction includes atleast one of a direction orthogonal to the predetermined plane, arotational direction around an axis orthogonal to the predeterminedplane and a rotational direction around an axis parallel to thepredetermined plane.
 5. The exposure apparatus according to claim 1,wherein the grating section has four scale members each of which isdisposed substantially parallel to the predetermined plane and has thereflective grating, and in the exposure operation, the positionalinformation of the second stage is measured by at least three of theheads that face at least three of the four scale members, respectively.6. The exposure apparatus according to claim 5, wherein one head of theat least three heads is switched to another head, as the second stage ismoved, and after the switching, the positional information of the secondstage is measured by at least three heads that include remaining headsand the another head, the remaining heads excluding the one head of theat least three heads used before the switching.
 7. The exposureapparatus according to claim 6, wherein before the switching, thepositional information of the second stage is measured by three of theheads that face three of the four scale members, respectively, one headof the three heads is switched to the another head that is differentfrom the three heads, and after the switching, the positionalinformation of the second stage is measured by three heads that includetwo remaining heads and the another head, the two remaining headsexcluding the one head of the three heads used before the switching. 8.The exposure apparatus according to claim 7, wherein for the switching,four heads respectively face the four scale members, the four headsincluding the three heads used before the switching and the anotherhead.
 9. The exposure apparatus according to claim 7, wherein thepositional information of the second stage is measured by four or threeof the heads that face four or three of the four scale members,respectively, and a change from one of a state and another state to theother of the state and the another state occurs, as the second stage ismoved, wherein in the state, the four heads face the four scale members,respectively, and in the another state, the three heads face the threescale members, respectively.
 10. The exposure apparatus according toclaim 1, wherein the first measurement system has another encoder systemdifferent from the encoder system, and measures the positionalinformation of the first stage with the another encoder system in theexposure operation.
 11. The exposure apparatus according to claim 1,further comprising: a nozzle member provided to surround a lens that isdisposed closest to an image plane side, of a plurality of opticalelements of the projection optical system, the nozzle member having alower surface to which the substrate is placed facing, and locallyforming a liquid immersion area with the liquid under the lens, whereinin the exposure operation, the substrate is placed to face the lowersurface of the nozzle member by the second stage, and the substrate isexposed with the illumination light via the projection optical systemand the liquid of the liquid immersion area.
 12. The exposure apparatusaccording to claim 11, wherein the other of the grating section and theheads is provided at the frame member so that the other of the gratingsection and the heads is disposed on an outer side of the nozzle memberwith respect to the projection optical system.
 13. The exposureapparatus according to claim 12, wherein the nozzle member is providedat the frame member or another frame member different from the framemember so that the lower surface is disposed lower than an emittingsurface of the lens.
 14. The exposure apparatus according to claim 12,wherein the second stage has a holder to hold the substrate, and holdsthe substrate in a recessed portion, where the holder is disposed, of anupper surface of the second stage so that a surface of the substrate andthe upper surface of the second stage are substantially flush, and thesecond stage maintains, with the upper surface, at least a part of theliquid immersion area that moves off from the substrate held in therecessed portion.
 15. The exposure apparatus according to claim 11,further comprising: a base member on which the second stage is disposedbelow the nozzle member, wherein the second stage system has a thirdstage disposed on the base member, positional information of the thirdstage is measured by the encoder system, and the third stage is moved bythe second drive system, and the controller controls the second drivesystem so that the third stage is moved from one side to the other sidein the first direction in order to cause the third stage to come closeto the second stage that is placed facing the projection optical system,and also the second and the third stages that have come close togetherare moved from the one side to the other side in the first direction inorder to place the third stage to face the projection optical systeminstead of the second stage while substantially maintaining the liquidimmersion area under the lens.
 16. The exposure apparatus according toclaim 15, wherein the controller controls the second drive system sothat, in the exposure operation, the second stage is moved from the oneside to the other side in the first direction in order to perform thescanning exposure via the projection optical system and the liquid ofthe liquid immersion area, from an area located on the other side in thefirst direction, of a plurality of areas on the substrate.
 17. Theexposure apparatus according to claim 16, wherein the controllercontrols the second drive system so that, in the exposure operation,exposure of a step-and-scan method is performed with respect to areasdisposed in line in the second direction, of the plurality of areas onthe substrate, in the exposure of the step-and-scan method the scanningexposure and movement of the substrate in the second direction beingrepeated.
 18. The exposure apparatus according to claim 17, wherein thecontroller controls the second drive system so that, in the exposureoperation, the third stage comes close, from the one side in the firstdirection, to the second stage that is moved from the one side to theother side in the first direction and also the third stage is moved fromthe one side to the other side in the first direction concurrently withthe movement of the second stage.
 19. The exposure apparatus accordingto claim 17, wherein the third stage holds a substrate, and thecontroller controls the second drive system so that an exposureoperation of a plurality of substrates is performed using the second andthe third stages alternately and also movement of the second and thethird stages that have come close together is performed following theexposure operation.
 20. The exposure apparatus according to claim 17,wherein the third stage has at least one measurement member that detectsthe illumination light via the projection optical system and the liquidof the liquid immersion area, and at least one of illuminancemeasurement, aerial image measurement and wavefront aberrationmeasurement is performed by the at least one measurement member.
 21. Theexposure apparatus according to claim 17, further comprising: an aerialimage measurement device that detects, via a slit pattern, an imageprojected via the projection optical system and the liquid of the liquidimmersion area, the slit pattern being disposed on an upper surface ofthe second stage, wherein in detection of the image, the positionalinformation of the second stage is measured by the encoder system, andthe controller controls the second drive system so that the image isprojected on the slit pattern following movement of the second and thethird stages that have come close together and also the scanningexposure is performed following the detection of the image.
 22. Theexposure apparatus according to claim 21, wherein the slit pattern isdisposed on the one side in the first direction on the upper surface ofthe second stage, and the controller controls the second drive system sothat the second stage placed facing the projection optical system ismoved from the one side to the other side in the first direction, inorder to perform the scanning exposure following the detection of theimage.
 23. The exposure apparatus according to claim 21, furthercomprising: a first detection system that is disposed spaced apart fromthe projection optical system in the first direction, and detects a markof the substrate and a fiducial mark disposed on the upper surface ofthe second stage, wherein in a detection operation of the marks, thepositional information of the second stage is measured by the encodersystem, and in the exposure operation, alignment between the mask andthe substrate is performed based on detection information of the firstdetection system and the aerial image measurement device.
 24. Theexposure apparatus according to claim 23, further comprising: a seconddetection system different from the first detection system, that isdisposed spaced apart from the projection optical system in the firstdirection, and detects positional information of the substrate in athird direction orthogonal to the predetermined plane, wherein in adetection operation of the substrate, the positional information of thesecond stage is measured by the encoder system, and in the exposureoperation, focus-leveling control of a pattern image of the mask and thesubstrate is performed based on detection information of the seconddetection system and the aerial image measurement device, the patternimage being projected via the projection optical system and the liquidof the liquid immersion area.
 25. The exposure apparatus according toclaim 24, wherein the controller controls the second drive system sothat the image is detected, via the slit pattern, at each of positionsdifferent from each other in the third direction, in order to acquirefocus information of the projection optical system that is used in thefocus-leveling control.
 26. A device manufacturing method, comprising:exposing a wafer as the substrate using the exposure apparatus accordingto claim 1; and developing the wafer that has been exposed.
 27. Anexposure method of exposing a substrate with an illumination light via aprojection optical system, the method comprising: holding a mask with afirst stage disposed above the projection optical system, the firststage being moved at least in a first direction within a predeterminedplane orthogonal to an optical axis of the projection optical system;holding the substrate with a second stage disposed below the projectionoptical system, the second stage being moved at least in the firstdirection and a second direction orthogonal to each other within thepredetermined plane; measuring positional information of the first stageand positional information of the second stage with a first measurementsystem and a second measurement system, the second measurement systemhaving an encoder system in which one of a grating section and heads isprovided at the second stage and the other of the grating section andthe heads is provided at a frame member so that the other of the gratingsection and the heads faces the second stage, and which measures thepositional information of the second stage with a plurality of the headsthat face the grating section, the grating section having a reflectivegrating that is periodic in a direction parallel to the predeterminedplane, and the frame member supporting the projection optical system;and controlling movement of the first and the second stages based oncorrection information for compensating for a measurement error of theencoder system and measurement information of the first and the secondmeasurement systems so that, in an exposure operation of the substrate,scanning exposure in which the mask and the substrate are each movedrelative to the illumination light is performed with the first directionserving as a scanning direction and also the measurement error iscompensated, the measurement error occurring due to a difference betweena position of a reference plane and a position of a grating surface ofthe grating section in a third direction orthogonal to the predeterminedplane, the reference plane being a reference plane for position controlor positioning of the second stage or a reference plane with which thesubstrate coincides in the exposure operation.
 28. The exposure methodaccording to claim 27, wherein the grating section has four scalemembers each of which is disposed substantially parallel to thepredetermined plane and has the reflective grating, and in the exposureoperation, the positional information of the second stage is measured byat least three of the heads that face at least three of the four scalemembers, respectively.
 29. The exposure method according to claim 28,wherein one head of the at least three heads is switched to anotherhead, as the second stage is moved, and after the switching, thepositional information of the second stage is measured by at least threeheads that include remaining heads and the another head, the remainingheads excluding the one head of the at least three heads used before theswitching.
 30. The exposure method according to claim 29, wherein beforethe switching, the positional information of the second stage ismeasured by three of the heads that face three of the four scalemembers, respectively, one head of the three heads is switched to theanother head that is different from the three heads, and after theswitching, the positional information of the second stage is measured bythree heads that include two remaining heads and the another head, thetwo remaining heads excluding the one head of the three heads usedbefore the switching.
 31. The exposure method according to claim 30,wherein for the switching, four heads respectively face the four scalemembers, the four heads including the three heads used before theswitching and the another head.
 32. The exposure method according toclaim 30, wherein the positional information of the second stage ismeasured by four or three of the heads that face four or three of thefour scale members, respectively, and a change from one of a state andanother state to the other of the state and the another state occurs, asthe second stage is moved, wherein in the state, the four heads face thefour scale members, respectively, and in the another state, the threeheads face the three scale members, respectively.
 33. The exposuremethod according to claim 27, wherein a liquid immersion area is locallyformed with a liquid under a lens, by a nozzle member provided tosurround the lens and having a lower surface to which the substrate isplaced facing, the lens being disposed closest to an image plane side,of a plurality of optical elements of the projection optical system, andin the exposure operation, the substrate is placed to face the lowersurface of the nozzle member by the second stage, and the substrate isexposed with the illumination light via the projection optical systemand the liquid of the liquid immersion area.
 34. The exposure methodaccording to claim 33, wherein the substrate is held in a recessedportion of an upper surface of the second stage so that a surface of thesubstrate and the upper surface are substantially flush, the secondstage is moved below the other of the grating section and the headsprovided at the frame member so that the other of the grating sectionand the heads is disposed on an outer side of the nozzle member withrespect to the projection optical system, and at least a part of theliquid immersion area that moves off from the substrate held in therecessed portion is maintained with the upper surface.
 35. The exposuremethod according to claim 33, wherein the second stage and a third stageare moved on a base member disposed below the nozzle member, andpositional information of the third stage is measured by the encodersystem, and the third stage is moved from one side to the other side inthe first direction so that the third stage comes close to the secondstage that is placed facing the projection optical system, and also thesecond and the third stages that have come close together are moved fromthe one side to the other side in the first direction so that the thirdstage is placed to face the projection optical system instead of thesecond stage while substantially maintaining the liquid immersion areaunder the lens.
 36. The exposure method according to claim 35, whereinin the exposure operation, the second stage is moved from the one sideto the other side in the first direction so that the scanning exposureis performed via the projection optical system and the liquid of theliquid immersion area, from an area located on the other side in thefirst direction, of a plurality of areas on the substrate, and exposureof a step-and-scan method is performed with respect to areas disposed inline in the second direction, of the plurality of areas on thesubstrate, in the exposure of the step-and-scan method the scanningexposure and movement of the substrate in the second direction beingrepeated.
 37. The exposure method according to claim 36, wherein in theexposure operation, the third stage comes close, from the one side inthe first direction, to the second stage that is moved from the one sideto the other side in the first direction and also the third stage ismoved from the one side to the other side in the first directionconcurrently with the movement of the second stage.
 38. The exposuremethod according to claim 36, wherein a substrate is held by the thirdstage, and an exposure operation of a plurality of substrates isperformed using the second and the third stages alternately and alsomovement of the second and the third stages that have come closetogether is performed following the exposure operation.
 39. The exposuremethod according to claim 36, wherein at least one of illuminancemeasurement, aerial image measurement and wavefront aberrationmeasurement is performed by at least one measurement member that isprovided at the third stage and detects the illumination light via theprojection optical system and the liquid of the liquid immersion area.40. The exposure method according to claim 36, wherein an imageprojected via the projection optical system and the liquid of the liquidimmersion area is detected by an aerial image measurement device via aslit pattern disposed on an upper surface of the second stage, and indetection of the image, the positional information of the second stageis measured by the encoder system, and the image is projected on theslit pattern following movement of the second and the third stages thathave come close together and also the scanning exposure is performedfollowing the detection of the image.
 41. The exposure method accordingto claim 40, wherein a mark of the substrate and a fiducial markdisposed on the upper surface of the second stage are detected by afirst detection system disposed spaced apart from the projection opticalsystem in the first direction, in a detection operation of the marks,the positional information of the second stage is measured by theencoder system, and in the exposure operation, alignment between themask and the substrate is performed based on detection information ofthe first detection system and the aerial image measurement device. 42.The exposure method according to claim 41, wherein positionalinformation of the substrate in the third direction is detected by asecond detection system disposed spaced apart from the projectionoptical system in the first direction and different from the firstdetection system, and in a detection operation of the substrate, thepositional information of the second stage is measured by the encodersystem, and in the exposure operation, focus-leveling control of apattern image of the mask and the substrate is performed based ondetection information of the second detection system and the aerialimage measurement device, the pattern image being projected via theprojection optical system and the liquid of the liquid immersion area.43. A device manufacturing method, comprising: exposing a wafer as thesubstrate using the exposure method according to claim 27; anddeveloping the wafer that has been exposed.
 44. A making method of anexposure apparatus that exposes a substrate with an illumination lightvia a projection optical system, the method comprising: providing aframe member that supports the projection optical system; providing afirst stage system that has a first stage and a first drive system, andmoves the first stage at least in a first direction within apredetermined plane orthogonal to an optical axis of the projectionoptical system, the first stage being disposed above the projectionoptical system and holding a mask illuminated with the illuminationlight, and the first drive system including a first motor to drive thefirst stage; providing a second stage system that has a second stage anda second drive system, and moves the second stage at least in the firstdirection and a second direction orthogonal to each other within thepredetermined plane, the second stage being disposed below theprojection optical system and holding the substrate, and the seconddrive system including a second motor to drive the second stage;providing a first measurement system and a second measurement systemthat measure positional information of the first stage and positionalinformation of the second stage, respectively, the second measurementsystem having an encoder system in which one of a grating section andheads is provided at the second stage and the other of the gratingsection and the heads is provided at the frame member so that the otherof the grating section and the heads faces the second stage, and whichmeasures the positional information of the second stage with a pluralityof the heads that face the grating section, and the grating sectionhaving a reflective grating that is periodic in a direction parallel tothe predetermined plane; and providing a controller coupled to the firstand the second stage systems and the first and the second measurementsystems, wherein the controller controls the first and the second drivesystems based on measurement information of the first and the secondmeasurement systems and correction information for compensating for ameasurement error of the encoder system related to a measurementdirection of the positional information by the heads so that, in anexposure operation of the substrate, scanning exposure in which the maskand the substrate are each moved relative to the illumination light isperformed with the first direction serving as a scanning direction andalso the measurement error is compensated, the measurement erroroccurring due to a relative motion between the heads and the gratingsection in a different direction that is different from the measurementdirection.